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    Wyświetlanie 1-81 z 81
    Tytuł:
    Rayleigh Region in Amorphous and Nanocrystaline FINEMET Alloy
    Autorzy:
    Novák, L.
    Kováč, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1200807.pdf
    Data publikacji:
    2014-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.50.Kj
    75.50.Tt
    75.60.Ch
    75.60.Ej
    75.60.Jk
    Opis:
    The magnetization processes in region of small excitation magnetic fields - Rayleigh region, were investigated on the amorphous and nanocrystalline FINEMET ribbons. The significant differences in behaviour of these materials were found. This could be explained by the difference in the value of magnetoelastic anisotropy as well as by the different thickness of the domain walls in these materials.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 1; 126-127
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Minor Loop Scaling Rules for Finemet Type Soft Magnetic Cores
    Autorzy:
    Varga, L.
    Kováč, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1367508.pdf
    Data publikacji:
    2014-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.50.Bb
    75.50.Kj
    75.60.-d
    75.60.Ej
    Opis:
    The validity of the Steinmetz law $(P=K B^{n})$ has been analyzed using the tanh model, by splitting the minor loops in three or two components, corresponding to different magnetization processes at different excitation levels. It is shown that the original Steinmetz law with the exponent n=1.6 is valid only at and above the coercive field, for intermediate and high induction values, where all the three magnetization processes are present. At small magnetization levels the exponent is about 3, much higher than the original proposed value.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 1; 156-157
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Magnetic Transition in La$\text{}_{1}\text{}_{/}\text{}_{3}$ Nd$\text{}_{1}\text{}_{/}\text{}_{3}$ Ca$\text{}_{1}\text{}_{/}\text{}_{3}$ MnO$\text{}_{3}$ Perovskite Induced by Electric Field at a Given Magnetic Field
    Autorzy:
    Baszyński, J.
    Kowalczyk, A.
    Kováč, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/2013719.pdf
    Data publikacji:
    2000-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.30.Et
    Opis:
    We report the discovery of new effect in La$\text{}_{1}\text{}_{/}\text{}_{3}$ Nd$\text{}_{1}\text{}_{/}\text{}_{3}$ Ca$\text{}_{1}\text{}_{/}\text{}_{3}$ MnO$\text{}_{3}$ - the jump of magnetization induced by external electric field E (2.5-4)V/cm at a given magnetic field H (18-25) kOe at T=4.2 K. This effect is large when compared with a metamagnetic transition induced by the magnetic field in many substances. The origin of the magnetization jump induced by external electric field has not yet been explained. We assume that this transition is induced by the hopping of E-excited e$\text{}_{g}$ electrons and that this is a source of a jumpwise increase in magnetization in the non-collinear magnetic phase within the perovskite. This effect can be attributed to a strong coupling between carriers induced by the electric field (the conduction electrons e$\text{}_{g}$), and the local magnetic moments (t$\text{}_{2g}$-localized spins) through a mechanism of the Zener double exchange.
    Źródło:
    Acta Physica Polonica A; 2000, 97, 5; 879-882
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Exchange Bias in Iron-Oxide Particles Nanocasted in Periodic Porous Silica
    Autorzy:
    Zeleňáková, A.
    Kováč, J.
    Zeleňák, V.
    Powiązania:
    https://bibliotekanauki.pl/articles/1810584.pdf
    Data publikacji:
    2009-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.46.Df
    68.37.Lp
    75.20.-g
    75.30.Cr
    Opis:
    Iron-oxide nanoparticles were nanocasted in the periodic mesoporous silica matrix, consisting of two-dimensional hexagonally ordered channel system with the mean diameter of the channels about 7 nm. The magnetic measurements of dc magnetization confirm behavior typical of a superparamagnetic system, such as the irreversibility of the zero-field-cooled and field-cooled curves, presence of a maximum in zero-field-cooled curve related with blocking temperature $T_C$ and revealing of coercivity $H_C$ below $T_C$. The existence of negative exchange bias effect below $T_C$ was confirmed in our system represented by value of exchange bias field $H_{EB}$=-970 Oe measured at the temperature 2 K.
    Źródło:
    Acta Physica Polonica A; 2009, 115, 1; 357-359
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Mechanochemical Preparation and Magnetic Properties of Fe₃O₄/ZnS Nanocomposite
    Autorzy:
    Bujňáková, Z.
    Zorkovská, A.
    Kováč, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1032141.pdf
    Data publikacji:
    2017-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    81.07.Bc
    81.20.Ev
    81.20.Wk
    Opis:
    Powder nanocomposite of Fe₃O₄/ZnS was prepared by mechanochemical synthesis in a planetary ball mill. In this reaction natural magnetite mineral Fe₃O₄ was used, together with zinc acetate (CH₃COO)₂Zn·2H₂O and sodium sulfide Na₂S·9H₂O, as precursors for the zinc sulfide ZnS. X-ray diffraction revealed that the sample is composed of small nanocrystalline particles, containing Fe₃O₄ and ZnS. The non-milled magnetite showed distinctive Verwey transition at around 120 K, this becomes suppressed after milling, as a consequence of structural disorder and presence of defects. Moreover, the reduction of saturation magnetization from 91 A m²/kg to 69.2 A m²/kg was observed, as a consequence of the milling process. The magnetization of the Fe₃O₄/ZnS nanocomposite was the lowest (34.5 A m²/kg), due to the milling and to the decreased weight fraction of the ferrimagnetic component. Nevertheless, the Fe₃O₄/ZnS sample demonstrates ferrimagnetic behavior as well, and its structure is less perturbed by milling, the Verwey transition, although less impressive, but is preserved.
    Źródło:
    Acta Physica Polonica A; 2017, 131, 4; 1120-1122
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of Pulse Heating on Rayleigh Area of Amorphous FINEMET-Type Alloy
    Autorzy:
    Novák, L.
    Kováč, J.
    Hubač, L.
    Powiązania:
    https://bibliotekanauki.pl/articles/1032143.pdf
    Data publikacji:
    2017-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.20.En
    75.50.Kj
    75.60.Nt
    75.60.Jk
    Opis:
    The effect of pulse annealing on magnetization processes in FINEMET-type alloy in weak magnetic fields (the Rayleigh area) is studied in this paper. Rapidly quenched FINEMET ribbon in the original amorphous state was chosen for the study. The significant differences in behavior of studied materials are ascribed to the differences in internal mechanical stresses, which bring about the changes in total magnetic anisotropy and consequently also changes in domain walls thickness.
    Źródło:
    Acta Physica Polonica A; 2017, 131, 4; 753-755
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Study of the Magnetization Processes in Amorphous and Nanocrystalline FINEMET by the Numerical Decomposition of the Hysteresis Loops
    Autorzy:
    Kováč, J.
    Novák, L.
    Varga, L.
    Powiązania:
    https://bibliotekanauki.pl/articles/1032185.pdf
    Data publikacji:
    2017-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.60.-d
    75.60.Ej
    Opis:
    The magnetization processes in amorphous and nanocrystalline FINEMET ribbons were studied by the numerical decomposition of the quasi-static hysteresis loop to the contributions of the domain wall movement, the domain rotations, and the domain wall annihilation and nucleation processes following the hyperbolic T(x) model of hysteresis. The hysteresis data measured during decrease of the excitation magnetic field were used for the separation of these processes. The significant differences in behavior of these two materials were found. In amorphous state the domain rotations component dominates whereas in nanocrystalline state the domain wall movement component prevails. These differences are reflected in the anisotropy field distributions as well.
    Źródło:
    Acta Physica Polonica A; 2017, 131, 4; 732-734
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    AC Magnetic Susceptibility Study of Fe and Co Based Nanoparticles
    Autorzy:
    Zeleňáková, A.
    Kováč, J.
    Zeleňák, V.
    Powiązania:
    https://bibliotekanauki.pl/articles/1368479.pdf
    Data publikacji:
    2014-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.75.Fk
    81.05.Rm
    75.40.Cx
    Opis:
    We have investigated magnetic properties of three different samples composed of magnetic Fe or Co core and protective Au or Pt metallic shell, namely Fe@Au, Co@Au and Fe@Pt samples, with sizes of about 10 nm, 8 nm and 5 nm respectively. We have measured and analysed the experimental data of real and imaginary component of ac susceptibility through theoretical laws for non-interacting and interacting particles and we have estimated the strength of their magnetic interactions. Our analyses showed the increase of inter-particle interactions with decreasing particles size.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 1; 222-223
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Reliability analysis of forest machines due to FMEA method
    Autorzy:
    Ťavoda, P.
    Kováč, J.
    Łukaszczyk, Z. Ł.
    Powiązania:
    https://bibliotekanauki.pl/articles/409738.pdf
    Data publikacji:
    2018
    Wydawca:
    STE GROUP
    Tematy:
    reliability
    FMEA method
    forest machines
    maintenance
    Opis:
    The article deals with the research of operational reliability of forest felling machines with the method FMEA (Failure Mode and Effect Analysis) and its implementation for observed machines in the organization. Forwarders 810D by John Deere were chosen for this research. The research was realized in real operational conditions. Application of the FMEA method allows flexibility in case of unexpected situations and optimization of human potential abilities. FMEA tool is a tool preventing outages operational reliability and preventive tool for ensuring the maintenance of facilities. This paper explores and verifies the operational reliability theory in practical real-world conditions, resulting in a reduction in operating (variable) costs, minimization of failures and readiness and increased performance of observed machines.
    Źródło:
    Management Systems in Production Engineering; 2018, 4 (26); 200-206
    2299-0461
    Pojawia się w:
    Management Systems in Production Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of 1D Ordering on Magnetic Properties of Iron Nanoparticles coated by Silica Shell
    Autorzy:
    Zeleňáková, A.
    Hrubovčák, P.
    Zeleňák, V.
    Kováč, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1030766.pdf
    Data publikacji:
    2018-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.40.Cx
    75.75.Fk
    68.37.Og
    Opis:
    Peculiar magnetic properties of 1D arranged composite consisting of Fe nanoparticles coated by insulating SiO2 layer were studied. Silica layer promotes the self-organization of 4 nm iron nanoparticles to the chain-like structures. Magnetization study shows that prepared nanoparticles exhibit very strong inter-particle magnetic interactions, which lead to long-range ordering of nanoparticles magnetic moments. Magnetic properties show superferromagnetic behaviour. The low value of room temperature coercivity, the existence of electrical insulating silica layer and small size of iron nanoparticles favour studied material for potential usage in microelectronic devices designed for high voltage signals modulated by high frequencies.
    Źródło:
    Acta Physica Polonica A; 2018, 133, 3; 561-563
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    On the Mechanism of H-Induced Curie-Point Relaxation in Fe-Based Glassy Alloys
    Autorzy:
    Balla, S.
    Kováč, J.
    Novák, L.
    Lovas, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1813523.pdf
    Data publikacji:
    2008-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.23.Cq
    71.55.Jv
    75.50.Kj
    81.40.Rs
    Opis:
    In Fe based glasses not solely the stress-sensitive magnetic properties, but also the amorphous Curie temperature $(T_C^{am})$ can be altered by hydrogen absorption or due to the low temperature "heat treatments" in liquid $N_2$ (-196°C). The sign and magnitude of this $T_C^{am}$ shift is strongly compositional dependent, but it is also influenced by the thermal history of glasses (heat treatments). In this paper new experimental results are presented, which were obtained on FeCrB alloys, supporting the previous observations. An attempt of interpretation of the results is also made, which is based on the existence of the quenched-in phase reminiscences, being inherited from the liquid structure.
    Źródło:
    Acta Physica Polonica A; 2008, 113, 1; 55-59
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Magnetic Study of the Fe Coated by Au Nanoparticles
    Autorzy:
    Zeleňáková, A.
    Kováč, J.
    Kavečanský, V.
    Zeleňák, V.
    Powiązania:
    https://bibliotekanauki.pl/articles/1813874.pdf
    Data publikacji:
    2008-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.46.Df
    68.37.Lp
    75.20.-g
    75.30.Cr
    Opis:
    Nanosized iron-gold magnetic nanoparticles with an average particle size 10 nm were prepared by a reverse micelle method. The magnetic properties measurements of DC and AC magnetization confirm behaviour typical of a superparamagnetic system, such as the irreversibility of the zero-field-cooled and field-cooled curves, the frequency dependence of a blocking temperature $T_B$, and revealing of coercivity H_C below blocking temperature. The quantitative analysis of AC susceptibility due to value of parameter $C_1$ = Δ$T_B$/($T_B$ Δ log f)=0.0242 confirming the existence of inter-particle interaction in our system.
    Źródło:
    Acta Physica Polonica A; 2008, 113, 1; 533-536
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Superparamagnetism in Cobalt Nanoparticles Coated by Protective Gold Layer
    Autorzy:
    Hrubovčák, P.
    Zeleňáková, A.
    Zeleňák, V.
    Kováč, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1368320.pdf
    Data publikacji:
    2014-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.40.Cx
    75.75.Fk
    68.37.Og
    Opis:
    In this work we present the study on structural and magnetic properties of fine cobalt nanoparticles coated by protective gold layer synthetized by microemulsion method. Structural measurements (powder XRD, HRTEM) confirmed spherical shape of the particles, their nanocrystalline character and presence of individual Co and Au phases. Investigation of magnetic properties of the particles revealed superparamagnetic behavior at higher temperatures and magnetic hysteresis at low temperatures. Average magnetic moment of individual particle $m_{p}~86.3μ_{B}$ was established. The critical temperature, below which the magnetic moments of the particles are blocked, was $T_{B}$=6 K. Investigation of magnetic relaxation processes via magnetic susceptibility, detected one maximum attributed to single relaxation process, present in the particles. Obtained data, interpreted in terms of Neél-Arrhenius and Vogel-Fulcher theoretical models, confirmed the presence of strong magnetic interparticle interactions.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 1; 216-217
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Clean bulk YBaCuO superconductors doped by paramagnetic ions of Sm and Yb
    Autorzy:
    Jirsa, M.
    Volochová, D.
    Kováč, J.
    Diko, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1054700.pdf
    Data publikacji:
    2017-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    74.25.Ha
    74.25.Op
    74.25.Sv
    74.60.Ge
    74.72.-h
    Opis:
    The recently developed clean cuprate technology was employed to study the effect of tiny amounts of paramagnetic Yb and Sm ions on electromagnetic properties of bulk YBaCuO. Small samples of about 1.5×1.5×0.5 mm³ were measured by vibrating sample magnetometer in the field range ±9 T and temperatures 30 K to 10 K in the non-superconducting tetragonal state and 300 K to 70 K in the orthorhombic, superconducting state. In the latter case, we observed the reversible paramagnetic moment above T_{C}, similar as in the tetragonal state. Below T_{C} an irreversible magnetic moment was observed from which critical current density, J_c, was evaluated using the extended Bean model. The effect of doping by Yb and Sm ions on J_c was studied and a correlation between J_c and the total paramagnetic moment was found. Both J_c(B) and the normalized pinning force density as a function of the reduced magnetic field were analyzed in terms of the classical model and discussed with respect to the material anisotropy, giving us at least a rough idea on the type of the effective pinning type and mechanism.
    Źródło:
    Acta Physica Polonica A; 2017, 131, 4; 1027-1029
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Room-Temperature Ferromagnetism in Zn-Mn-O, X-Ray Photoemission Surface Study
    Autorzy:
    Milivojević, D.
    Babić-Stojić, B.
    Blanuša, J.
    Kovač, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1503685.pdf
    Data publikacji:
    2011-08
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.50.Pp
    81.40.Rs
    81.70.Jb
    82.80.Pv
    Opis:
    Room temperature ferromagnetic properties of Zn-Mn-O show evident dependence on manganese concentration and preparation conditions. We systematically studied series of samples with manganese concentration ranging from 0 to 10 at.%, prepared in air at thermal treatment temperatures ranging from 400 to 900°C. The samples were investigated by X-ray diffraction, TEM, magnetization measurements and XPS spectroscopy. XPS analyses of surface composition, chemical bonding and XPS depth profiling were successfully employed on powder revealing the chemical composition at the surface of the grains and underneath. The study emphasizes important role of the grain surface in observed room temperature ferromagnetism. It seems that the ferromagnetic phase is correlated with oxygen build up at the surface.
    Źródło:
    Acta Physica Polonica A; 2011, 120, 2; 311-315
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    $[FeCl_{4}]¯$ Ionic Liquid Based Ferrofluids
    Autorzy:
    Parnica, J.
    Kesa, P.
    Kovac, J.
    Timko, M.
    Antalik, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1368745.pdf
    Data publikacji:
    2014-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    87.64.kp
    75.50.Bb
    47.65.Cb
    75.50.Mm
    Opis:
    Magnetic ionic liquids derived from hydrochloride methyl ester alanine amino acids (AA) and $FeCl_{3}$ were synthesized in ethanol and their magnetic properties were investigated. Iron (III) chloride forms ionic liquid in ethanol at saturated concentrations by the transfer of Cl¯ anion from one molecule of $FeCl_{3}$ to the other molecule with the creation of tetrachloro ferrate anion $[FeCl_{4}]$¯ as well as dimer $[Fe_{2}Cl_{7}]$¯. Raman scattering indicates that after addition of hydrochloride methyl ester alanine to ethanol solutions of $FeCl_{3}$ increase the intensities of signal at the frequencies at 318 $cm^{-1}$ and 380 $cm^{-1}$ as markers for the presence of $[FeCl_{4}]$¯ and $[Fe_{2}Cl_{7}]$¯ complexes. The magnetization at room temperature showed in both samples a linear dependence on the applied magnetic field. On the other hand, in the Raman scattering experiments the magnetization is smaller for $FeCl_{3}$ sample in the presence of methyl ester alanine.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 1; 276-277
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Effect of Polymer Immobilization on Magnetic Properties of Magnetosomes
    Autorzy:
    Timko, M.
    Džarová, A.
    Kovač, J.
    Kopčanský, P.
    Gojzewski, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/1535115.pdf
    Data publikacji:
    2010-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.30.Cr
    75.30.Gw
    75.50.Mm
    75.50.Tt
    75.60.Ej
    Opis:
    The anisotropy of several PVA/magnetosomes magnetically textured films has been investigated from the point of view of magnetic properties. The thin film synthesized under the influence of a magnetic field (99 mT) shows the typical behavior of an anisotropic material. On sample textured in magnetic field the magnetisation loop measurements were performed in dependence on the direction of the external magnetic field with respect to the texture axis. The results of hysteresis measurements show that the magnetic field applied during the synthesis promotes an orientation of the chains of magnetosomes and permanently textured film is obtained after solidification. The obtained values for magnetic remanence and coercivity were dependent on the external magnetic field orientation and the alignment effect of particle moments may be clearly seen which is in agreement with the theoretical model of magnetic particle chains.
    Źródło:
    Acta Physica Polonica A; 2010, 118, 5; 995-997
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Physical Properties of "HTSC/Photosemiconductor" Micro- and Nanoplates Based Junctions
    Autorzy:
    Bunda, V.
    Bunda, S.
    Vashchuk, F.
    Feher, A.
    Kováč, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1535401.pdf
    Data publikacji:
    2010-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    85.25.Hv
    74.45.+c
    74.25.F-
    74.55.+v
    Opis:
    In this paper we report the formation process and electrophysical properties of 'high temperature superconductor $(YBa_2Cu_3O_{7 - x})$/photosemiconductor (BiOCl:Ti)' micro- and nanoplates based junction. The energy band model of ≪HTSC-semiconductor≫ junction is proposed.
    Źródło:
    Acta Physica Polonica A; 2010, 118, 5; 1040-1041
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Crystalline Structure, Stoichiometry and Magnetic Properties of the Morasko Meteorite
    Autorzy:
    Idzikowski, B.
    Kováč, J.
    Diko, P.
    Stankowski, W.
    Muszyński, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1535541.pdf
    Data publikacji:
    2010-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    91.65.Sn
    75.50.Bb
    67.80.dk
    Opis:
    The composition and structure of iron-nickel alloys smithereens extracted from the Morasko (Poland) Meteorite (fell ∿ 5 ka BP) were investigated by optical metallographic techniques, scanning electron microscopy and electron microprobe analysis, thermal analyses, magnetic measurements and X-ray diffraction. Microstructural analysis by scanning electron microscopy and optical microscopy has shown that the sample is composed from large grains of Fe-Ni alloy in which secondary phase crystals with well developed crystal habits and the size about 10 micrometers are distributed. Thermal analyses confirmed that the transformation from alpha to gamma Fe-Ni solid solution appearing as a function of temperature corresponds to about 5 wt% Ni in the Fe-Ni alloy. Possible scenario of the extraterrestrial sample solidification is related to the microstructural and magnetic behavior.
    Źródło:
    Acta Physica Polonica A; 2010, 118, 5; 1071-1073
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of spark plasma sintering on microstructure and properties of bulk LaCaSrMnO magnetocaloric materials
    Autorzy:
    Zmorayová, K.
    Antal, V.
    Kováč, J.
    Diko, P.
    Noudem, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1053176.pdf
    Data publikacji:
    2017-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.47.Lx
    61.72.-y
    75.30.Kz
    77.80.B-
    81.70.Pg
    81.20.Ev
    81.30.Fb
    Opis:
    Polycrystalline La_{0.67}Ca_{0.33-x}Sr_xMnO₃ (x=0.33, 0.03, 0) (LCSM) perovskite samples treated by spark plasma sintering technique were investigated. This study proved influence of the sintering temperature on microstructure of these perovskite ceramics. The thermogravimetric measurements revealed the possibility of increase of oxygen content in studied LCSM samples by additional annealing under oxygen atmosphere and low temperature. Finally, the effect of this annealing on magnetic properties was demonstrated.
    Źródło:
    Acta Physica Polonica A; 2017, 131, 4; 804-806
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Magnetic Properties of Fe@Pt Nanoparticles with Core/Shell Morphology
    Autorzy:
    Zeleňáková, A.
    Zeleňák, V.
    Bednarčík, J.
    Lauda, M.
    Kováč, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1535141.pdf
    Data publikacji:
    2010-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.75.Fk
    75.50.Vv
    75.40.Gb
    Opis:
    We have investigated the magnetic properties of iron nanoparticles coated by platinum shell prepared by chemical procedure. Magnetic measurements using SQUID magnetometer confirm the behaviour typical for a superparamagnetic system. From the M(H) loop at 300 K the magnetic moment of each particle $m_{P}$ ≈ $250 μ_{B}$ was calculated. The magnetic relaxation study by the in-phase χ' and out-of-phase χ" ac susceptibilities in frequency range 0.1-1000 Hz suggests the existence of two magnetic layers with different magnetic spin's dynamics and strong dipolar interactions between nanoparticles. The observed magnetic behaviour is caused by the blocking process of interacting superparamagnetic particles with magnetic iron core, diamagnetic platinum shell and spin-glass like behaviour magnetic interlayer between them.
    Źródło:
    Acta Physica Polonica A; 2010, 118, 5; 1002-1004
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Study of Composites Consisting of High-T$\text{}_{c}$ Superconductor and Fine Magnetic Particles
    Autorzy:
    Timko, M.
    Kopčanský, P.
    Kováč, J.
    Koneracká, M.
    Plecháček, V.
    Powiązania:
    https://bibliotekanauki.pl/articles/2013009.pdf
    Data publikacji:
    2000-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    74.72.Hs
    75.50.Tt
    Opis:
    The composite systems as a mixture of fine magnetic particles of Fe$\text{}_{3}$O$\text{}_{4}$ and superconducting powder such as Bi$\text{}_{1.8}$Pb$\text{}_{0.2}$Sr$\text{}_{2}$Ca$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{10+x}$ were prepared. The influence of internal magnetic field (generated by magnetic particles) on the superconducting properties of prepared composites were studied as a function of concentration of magnetic particles and their magnetic state. The observed data both of the shielding and the Meissner effect were compared with corresponding linear combination of pure signals of magnetite and superconductor, respectively. The large differences were observed for demagnetized samples. It means that result must be discussed in the frame of the distribution of internal magnetic field created by the magnetic particles.
    Źródło:
    Acta Physica Polonica A; 2000, 97, 3; 389-392
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Magnetic Properties of Thorium Ferricyanide
    Autorzy:
    Göbl, R.
    Zentková, M.
    Kavečanský, V.
    Kováč, J.
    Zentko, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/2013694.pdf
    Data publikacji:
    2000-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.30.Cr
    Opis:
    The magnetic properties of Th$\text{}_{3}$[Fe(CN)$\text{}_{6}$]·10H$\text{}_{2}$O were investigated. It was shown that this compound is antiferromagnetically ordered in the low temperature region. The observed antiferromagnetic ordering is stable only in the low field.
    Źródło:
    Acta Physica Polonica A; 2000, 97, 5; 835-838
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Magnetic Properties of Mechanochemically Synthesized Mixed Oxides
    Autorzy:
    Kostova, N.
    Zorkovská, A.
    Kováč, J.
    Velinov, N.
    Baláž, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1372521.pdf
    Data publikacji:
    2014-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    77.84.Bw
    75.60.-d
    76.80.+y
    61.05.cp
    81.07.Wx
    Opis:
    The mixed oxides $Fe_{2}O_{3}-ZnO$ have been obtained in nanocrystalline state by reactive milling in a high-energy planetary mill, from a stoichiometric mixture of hematite and ZnO. The magnetic properties of samples were evaluated by magnetization measurements and Mössbauer spectrometry. A post milling annealing promotes the solid state reaction and improves the zinc ferrite formation, paramagnetic $ZnFe_{2}O_{4}$ phase is formed. Further mechanical activation leads to structural transformation into Wüstite-type (FeZn)O mixed oxide, with ferromagnetic hysteresis and increased magnetization.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 1; 411-412
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Synthesis and Characterization of Magnetoferritin
    Autorzy:
    Mitróová, Z.
    Melníková, L.
    Kováč, J.
    Timko, M.
    Kopčanský, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1429123.pdf
    Data publikacji:
    2012-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.30.Cr
    75.50.Ee
    75.60.Ej
    75.50.Tt
    Opis:
    The paper presents detailed experimental study of synthesis and characterization a bioinorganic magnetic molecule - magnetoferritin. Magnetoferritin with loading of iron ions per protein molecule in the range from 300 to 3000 was prepared. Size distribution analysis (transmission electron microscopy, dynamic light scattering) shows spherical nanoparticles with particle size distribution from 2 to 12 nm, and hydrodynamic diameter from 12 to 25 nm. The thermomagnetic curves measured after cooling the sample in zero field (zero-field cooling) and under the presence of the measurement field (field cooling) show superparamagnetic behavior with the blocking temperature $T_{b}$ from 22 to 60 K and the magnetization loops measured below $T_{b}$ (at 2 K) show the hysteresis with coercive field from 20 to 30 kA/m depending on the concentration of the magnetic nanoparticles.
    Źródło:
    Acta Physica Polonica A; 2012, 121, 5-6; 1318-1320
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The effect of Sm addition on the microstructure and superconducting properties of YBCO bulk superconductors
    Autorzy:
    Volochová, D.
    Diko, P.
    Piovarči, S.
    Antal, V.
    Kováč, J.
    Jirsa, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1054772.pdf
    Data publikacji:
    2017-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    74.72.-h
    74.62.Dh
    81.10.Fq
    61.72.-y
    74.25.Ha
    74.25.Sv
    Opis:
    The effect of Sm addition on the microstructure and superconducting properties of Y-Ba-Cu-O (YBCO) bulk superconductors has been studied. Nominal composition: 1 mol YBa₂Cu₃O_{7-δ} + 0.25 mol Y₂O₃ + 1 wt% CeO₂ was enriched with different amounts of SmBa₂Cu₃O_y powder with the aim to increase critical current density, J_c, especially in higher magnetic fields by introducing additional pinning centers. Single grain YBCO bulk superconductors with SmBa₂Cu₃O_y (Y123-Sm) addition were prepared by the optimized top seeded melt growth process. Microstructure analysis, performed by polarized light microscope, revealed that SmBa₂Cu₃O_y addition leads to a higher amount of slightly coarser Y₂BaCuO₅ particles, which is related to lower critical current densities (J_c ≈ 6×10⁴ A/cm²) of the YBCO samples with SmBa₂Cu₃O_y addition in low magnetic fields. On the other hand, an enhancement of critical current density, J_c, in higher magnetic fields was observed for Y123-Sm samples. Moreover, a maximum trapped magnetic field, B_{tmax}, of 564 mT at 77 K in Y123-Sm, x=0.0025 sample (Ø 17.2 mm) was 43% higher than that for YBCO sample without any addition.
    Źródło:
    Acta Physica Polonica A; 2017, 131, 4; 1009-1011
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Magnetic Charcoal Supporting Silver as a Water Disinfectant
    Autorzy:
    Valušová, E.
    Antalík, M.
    Pristaš, P.
    Javorský, P.
    Kováč, J.
    Timko, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1201874.pdf
    Data publikacji:
    2014-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    81.05.Ni
    75.60.Ej
    75.47.Lx
    81.05.U-
    92.40.qc
    Opis:
    We investigated the magnetic behavior of charcoal composite with incorporated magnetite and silver ions. The magnetization curve measured at 282 K showed saturation magnetization of 8 emu/g. By benefiting from a mechanical process, the magnetic activated carbon, supporting silver ions (MCAG), acts as a magnetic filter uptaking the bacteria. This idea was confirmed by the DGGE analysis in which the bacterial DNA was detectable in the sediment after the treatment.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 1; 226-227
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Preparation and Complex Characterization of Magnetic Nanoparticles in Magnetic Fluid
    Autorzy:
    Kubovčíková, M.
    Antal, I.
    Kováč, J.
    Závišová, V.
    Koneracká, M.
    Kopčanský, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1201928.pdf
    Data publikacji:
    2014-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.75.Fk
    78.67.Bf
    36.40.Cg
    47.65.Cb
    75.50.Mm
    75.30.Cr
    Opis:
    This paper deals with the preparation and complex characterization of magnetite nanoparticles (MNPs), stabilized with sodium oleate (SO), by the routine methods such as infrared spectroscopy (FTIR), magnetic measurements, scanning electron microscopy (SEM) and dynamic light scattering (DLS). The FTIR spectra showed that SO molecules were linked to MNPs through chemical bonding. Magnetic measurements proved that the MNPs are superparamagnetic in nature. Four different methods were used to determine the size and size distribution of the MNPs: SEM, DLS, differential centrifugal sedimentation (DCS) and magnetic measurements. SEM analysis showed a relatively narrow size distribution of roughly spherical MNPs with a mean diameter of 61 nm. DLS analysis confirmed monodispersed MNPs production with hydrodynamic diameter of 75 nm. The size distribution determined by DCS was found to be 69 nm. Finally, the calculated magnetic core diameter obtained from magnetization curve was 10 nm. The obtained results demonstrate that SO coated MNPs fulfil the requirements for a useful drug delivery system.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 1; 268-269
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Critical Current Density and Microstructure of $NdBa_2Cu_3O_7$ Single Crystal
    Autorzy:
    Diko, P.
    Zmorayová, K.
    Šefčiková, M.
    Antal, V.
    Kováč, J.
    Yao, X.
    Powiązania:
    https://bibliotekanauki.pl/articles/1535339.pdf
    Data publikacji:
    2010-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    74.25.Ha
    74.25.Sv
    74.62.Bf
    Opis:
    The top-seeded solution growth method was used to grow NdBCOss single crystals in air. The microstructure of the samples has shown that the oxygenation crack structure developed in the single crystals. The intrinsic critical current density was estimated to be at least twice higher than the value of volume critical current density determined from the magnetization measurements.
    Źródło:
    Acta Physica Polonica A; 2010, 118, 5; 1028-1030
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Magnetic Characterization of $Co_2MnSi$ Heusler Microwires
    Autorzy:
    Ryba, T.
    Vargova, Z.
    Varga, R.
    Kováč, J.
    Zhukova, V.
    Zhukov, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1368011.pdf
    Data publikacji:
    2014-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.50.Cc
    75.30.Gw
    Opis:
    We report on the basic magnetic properties of glass-coated $Co_2MnSi$ Heusler microwires. Measurements of hysteresis loops in different directions show that easy magnetization axis coincides with the wire's axis. The frequency dependence of the coercive field has been measured at room temperature in the frequency range from 10 Hz to 10 kHz. The coercivity decreases with the frequency up to 100 Hz and then increases linearly up to 1 kHz.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 1; 196-197
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Preparation and Investigations of $Ni_{0.2}Zn_{0.8}Fe_2O_4$ Ferrite Nanofiber Membranes by Needleless Electrospinning Method
    Autorzy:
    Streckova, M.
    Mudra, E.
    Sebek, M.
    Sopcak, T.
    Dusza, J.
    Kovac, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1398266.pdf
    Data publikacji:
    2017-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.75.Cd
    75.50.Gg
    81.07.-b
    75.47.Lx
    Opis:
    The preparation of $Ni_{0.2}Zn_{0.8}Fe_2O_4$ nanofiber membranes by simple and versatile needleless electrospinning technique is presented. The single phase of spinel ferrite membrane was obtained after conventional thermal treatment of polyvinyl alcohol (PVA)/metal nitrate precursors at 800°C for 4 h in air. The formation of single-phase fibers was characterized using differential scanning calorimetry accompanied with thermogravimetric analysis. The surface morphology, microstructure and crystal structure were investigated by scanning electron microscopy, X-ray diffraction and transmission electron microscopy. The magnetic properties of the fibrous samples measured in the temperature range from 2 to 300 K verify a soft magnetic behavior, which is quite typical for ferrimagnetic spinel-type ferrites.
    Źródło:
    Acta Physica Polonica A; 2017, 131, 4; 729-731
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Structure and Transport Properties of La$\text{}_{0.75-x}$RE$\text{}_{x}$Ca$\text{}_{0.25}$MnO$\text{}_{3}$ (RE = Gd, Dy, Ho; 0≤ x≤0.75) Manganites
    Autorzy:
    Drozd, V.
    Pękała, M.
    Kovac, J.
    Skorvanek, I.
    Szymański, M.
    Nedilko, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/2041482.pdf
    Data publikacji:
    2004-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.47.Lx
    71.38.-k
    72.20.Ee
    75.50.Dd
    Opis:
    Structure and transport properties have been studied for a series of La$\text{}_{0.75-x}$RE$\text{}_{x}$Ca$\text{}_{0.25}$MnO$\text{}_{3}$ manganites with heavy rare earth ions of Gd, Dy, Ho substituting La with x=0, 0.10, 0.25, 0.50, and 0.75. Polycrystalline samples were prepared by the carbonate precipitation route. The oxygen content was determined by the iodometric titration. The X-ray investigations carried out by the powder method show that the unit cell volume gradually decreases and orthorhombic distortion of the lattice increases with rising RE content. Below the room temperature the electrical resistivity is of the semiconducting type for all the samples studied. Electrical resistivity vs. temperature dependences were analyzed within different models: simple thermal activation, Mott's variable range hopping, adiabatic, nonadiabatic, and bipolaron. The Curie temperatures of Gd, Dy, and Ho substituted manganites determined from magnetization measurements show that at 280 K all the samples are in the paramagnetic phase. The increasing RE fraction reduces magnetization at 4 K as compared to La$\text{}_{0.75}$Ca$\text{}_{0.25}$MnO$\text{}_{3}$.
    Źródło:
    Acta Physica Polonica A; 2004, 106, 5; 751-758
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Mechanochemically Synthesized CuFeSe₂ Nanoparticles and Their Properties
    Autorzy:
    Dutková, E.
    Škorvánek, I.
    Sayagués, M.
    Zorkovská, A.
    Kováč, J.
    Baláž, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1032137.pdf
    Data publikacji:
    2017-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    81.05.Hd
    81.07.Wx
    81.20.Wk
    Opis:
    The mechanochemical synthesis of nanocrystalline CuFeSe₂ particles prepared by high-energy milling in a planetary mill in an argon atmosphere from copper, iron, and selenium for 60 min is reported for the first time. The CuFeSe₂ nanoparticles crystallize in tetragonal structure with mean crystallite size of about 32±1 nm. High resolution transmission electron microscopy measurements confirmed the presence of agglomerates which are formed by small nanocrystalline domains (5-40 nm). The magnetic data revealed that paramagnetic CuFeSe₂ nanoparticles coexist with a small amount of ferromagnetic impurities at room temperature. The magnetic transition towards a weak ferromagnetic or ferrimagnetic behavior occurs in CuFeSe₂ at approximately 79 K. The band gap of the CuFeSe₂ particles is 0.95 eV which is wider than the band gap in bulk materials (0.16 eV), which could be in many aspects of application more beneficial.
    Źródło:
    Acta Physica Polonica A; 2017, 131, 4; 1156-1158
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Characterization of Carbon Nanotubes
    Autorzy:
    Jeníková, M.
    Zakuťanská, K.
    Kováč, J.
    Girman, V.
    Kopčanský, P.
    Tomašovičová, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/1032760.pdf
    Data publikacji:
    2017-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.48.De
    74.25.nd
    68.37.Lp
    75.75.-c
    Opis:
    The aim of the presented work was to characterize single-walled carbon nanotubes as well as multi-walled carbon nanotubes by transmission electron microscopy, the Raman spectroscopy and magnetization measurements to obtain information about their size, structure, and magnetic properties. We show that having different carbon nanotubes one can easily distinguish the single-wall or multi-wall carbon nanotubes and determine their quality. The obtained results show that carbon nanotubes can be diamagnetic or ferromagnetic depending on their structural parameters.
    Źródło:
    Acta Physica Polonica A; 2017, 131, 4; 952-954
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of Zn on Structure and Magnetic Properties of Rapid Quenched (Fe-Zn)-Cu-Nb-Si-B Alloys
    Autorzy:
    Kolesar, V.
    Michalik, S.
    Kovac, J.
    Girman, V.
    Sovak, P.
    Kollar, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1533958.pdf
    Data publikacji:
    2010-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.46.Hk
    75.50.Bb
    75.75.Cd
    Opis:
    The aim of this work was to study the influence of Zn on the formation of nanostructure in $Fe_{73.5 - x}Zn_xCu_1Nb_3Si_{13.5}B_9$ (x = 1, 3, 5) ribbons prepared by the melt-spinning technique. X-ray diffraction measurements proved amorphous state of the sample with x = 1. The sample with x = 3 contains a small fraction of Fe_3Si phase and the sample with x = 5 is in nanocrystalline state with the average grain size of about 25 nm. The reduced radial distribution function G(r) was calculated for local structure investigation. Increasing Zn content enhances crystallization during solidification which leads to increase of magnetocrystalline anisotropy and consequently to increase of coercivity.
    Źródło:
    Acta Physica Polonica A; 2010, 118, 5; 790-791
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Magnetic Properties of Bacterial Nanoparticles
    Autorzy:
    Timko, M.
    Džarová, A.
    Kováč, J.
    Kopčanský, P.
    Gojzewski, H.
    Szlaferek, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1810601.pdf
    Data publikacji:
    2009-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    47.65.Cb
    51.60.+a
    75.30.Gw
    75.50.Tt
    75.60.Nt
    75.60.Ej
    75.75.+a
    Opis:
    The objective of this study is to prepare and study magnetic properties of biological magnetic nanoparticles (magnetosomes) as a product of biomineralization process of magnetotactic bacteria Magnetospirillum sp. AMB-1. From temperature dependence of remanent magnetization and coercive field the Verwey transition is clearly seen at 105 K as a consequence of the large anisotropy along the chains of magnetosomes.
    Źródło:
    Acta Physica Polonica A; 2009, 115, 1; 381-383
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Andreev Reflection Spectroscopy Study of Spin Polarization in Co₂Cr(Fe)Al Heusler Alloys
    Autorzy:
    Hašková, V.
    Szabó, P.
    Kováč, J.
    Ryba, T.
    Vargová, Z.
    Varga, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/1385695.pdf
    Data publikacji:
    2015-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    72.25.Ba
    74.45.+c
    77.80.bg
    Opis:
    The present paper is dealing with the experimental study of the influence of Fe substitution on the Curie temperature and spin polarization in Co₂CrAl Heusler alloys. A recently successfully introduced new rapid quenching method has been used for the preparation of Co₂CrAl and $Co₂Cr_{0.6}Fe_{0.4}Al$ ribbon samples. The Curie temperatures have been determined from magnetization measurements being 378 K for Co₂CrAl and much above 400 K for $Co₂Cr_{0.6}Fe_{0.4}Al$. The spin polarization parameter P₀ of the studied samples has been estimated from point-contact Andreev reflexion spectroscopy measurements. In pure Co₂CrAlP₀ = 0.5 - 0.9, and in the case of $Co₂Cr_{0.6}Fe_{0.4}AlP₀$ = 0.4 - 0.9. Hence, it is shown that Fe substitution of Cr in $Co₂Cr_{1-x}FeₓAl$ Heusler alloys at a concentration of x=0.4 significantly increase the Curie temperature without marked influence on the spin polarization.
    Źródło:
    Acta Physica Polonica A; 2015, 127, 2; 377-378
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of Co Doping on Induced Anisotropy and Domain Structure in Magnetic Field Annealed $(Fe_{1-x}Co_x)_{79}Mo_8Cu_1B_{12}$
    Autorzy:
    Kunca, B.
    Marcin, J.
    Švec, P.
    Kováč, J.
    Švec Sr., P.
    Škorvánek, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/1398273.pdf
    Data publikacji:
    2017-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.30.Gw
    75.50.Tt
    75.60.Ch
    75.60.Nt
    Opis:
    The effect of heat treatment in applied magnetic field on the induced anisotropy and domain structure of $(Fe_{1-x}Co_x)_{79} Mo_8 Cu_1 B_{12}$ (x=0, 0.2, 0.5) nanocrystalline alloy system was investigated. A heat treatment of Co-doped samples under the application of longitudinal magnetic field resulted in squared hysteresis loops characterized by very low coercive field values. Sheared loops with tunable slope and good field linearity were obtained after annealing in transverse magnetic field. Corresponding domain structure showed uniform character, oriented in the direction parallel or perpendicular to the ribbon axis after longitudinal or transverse magnetic field annealing, respectively. No effect of magnetic field annealing was found in Co-free sample. Correlations between Co-doping, the Curie temperature, and soft magnetic properties after magnetic field annealing are discussed.
    Źródło:
    Acta Physica Polonica A; 2017, 131, 4; 759-761
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of RF ICP PECVD process parameters of diamond-like carbon films on DC bias and optical emission spectra
    Autorzy:
    Oleszkiewicz, W
    Markowski, J
    Srnanek, R
    Kijaszek, W
    Gryglewicz, J
    Kovac, J
    Tlaczala, M
    Powiązania:
    https://bibliotekanauki.pl/articles/173686.pdf
    Data publikacji:
    2013
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    PECVD
    diamond-like carbon layers
    OES
    Raman spectroscopy
    AFM
    Opis:
    The work presents the results of a research carried out with PlasmaLab Plus 100 system, manufactured by Oxford Instruments Company. The system was configured for deposition of diamond-like carbon films by ICP PECVD method. The change of an initial value of DC bias was investigated as a function of set values of the generator power (RF generator and ICP generator) in the constant power of the RF generator operation mode. The research shows that the value of DC bias nearly linearly depends on the RF generator power value and is affected only in a small degree by the power of ICP discharge. The capability of an installed OES spectrometer has been used to ensure the same starting conditions for the deposition processes of DLC films. The analysis of OES spectra of RF plasma discharge used in the deposition processes shows that the increase in ICP discharge power value results in the increased efficiency of the ionization process of a gaseous precursor (CH4). The quality of deposited DLC layers was examined by Raman spectroscopy. Basing on the acquired Raman spectra, the theoretical content of sp3 bonds in the structure of the film was estimated. The content is ranging from 30% to 65% and depends on ICP PECVD deposition process parameters.
    Źródło:
    Optica Applicata; 2013, 43, 1; 109-115
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of Temperature on Magnetization Processes in Amorphous Rapidly Solidified FeSiB/CoSiB Bilayer Ribbons
    Autorzy:
    Capik, M.
    Švec, P.
    Marcin, J.
    Kováč, J.
    Sopko, M.
    Janičkovič, D.
    Škorvánek, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/1200803.pdf
    Data publikacji:
    2014-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.50.Kj
    75.60.Ej
    75.80.+q
    Opis:
    Amorphous bilayers consisting of Fe-Si-B and Co-Si-B layers have been prepared by planar flow casting from a single crucible using a double-nozzle technique. Temperature dependencies of magnetization and hysteresis loops have been investigated in a wide temperature range. At room temperature, the effects of interlayer stresses, induced in material due to different thermal expansion coefficients of two mechanically interconnected soft magnetic layers, resulted in rounded hysteresis loops with flattened central part, indicating a dominant role of magnetization rotational processes. With an increase of measurement temperature, the interlayer stresses are relieved and the hysteresis loops became more squared.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 1; 120-121
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Magnetic Birefringence Study of the Magnetic Core Structure of Ferritin
    Autorzy:
    Koralewski, M.
    Pochylski, M.
    Mitróová, Z.
    Melníková, L.
    Kováč, J.
    Timko, M.
    Kopčanský, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1428622.pdf
    Data publikacji:
    2012-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    78.20.Ls
    87.15.-v
    87.85.jf
    Opis:
    Magnetically induced optical birefringence (Δ n) was measured for magnetoferritin and horse spleen ferritin aqueous suspensions. The Δ n for magnetoferritin was described in the frame of the Langevin formalism taking into account distribution of core diameter. The established average magnetic dipole moment and core diameter is equal to about 460 $μ_{B}$ and 3 nm, respectively. It was shown that magnetic birefringence and the Cotton-Mouton constant can be powerful parameters in identification of the magnetic core structure of ferritin, especially useful in biomedicine.
    Źródło:
    Acta Physica Polonica A; 2012, 121, 5-6; 1237-1239
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Microstructure and Magnetic Properties of La-Ca-Sr-Mn-O Perovskite Ceramics
    Autorzy:
    Zmorayova, K.
    Antal, V.
    Radusovska, M.
    Piovarci, S.
    Kováč, J.
    Kavecansky, V.
    Diko, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1367705.pdf
    Data publikacji:
    2014-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.30.Sg
    75.47.Lx
    77.80.Bh
    81.20.Ev
    81.30.Fb
    Opis:
    $La_{0.67}Ca_{0.33-x}Sr_{x}MnO_{3}$ (x=0.33; 0.03; 0) (LCSM) perovskite magnetocaloric ceramics were prepared by solid state synthesis in air and sintering at 1520°. The phase composition was checked by x-ray powder diffraction. Microstructure analyses were done by scanning electron microscopy. The influence of high pressure oxygenation on magnetisation behaviour is shown.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 1; 168-169
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Soft Magnetic Properties and Temperature Stability of Co-Fe-Zr-B Metallic Glasses
    Autorzy:
    Bednarčík, J.
    Kováč, J.
    Roth, S.
    Fűzer, J.
    Kollár, P.
    Varga, L.
    Franz, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/1813531.pdf
    Data publikacji:
    2008-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.50.Kj
    Opis:
    In the present work multicomponent Co-based alloys with nominal composition $Co_{72-x}Fe_xZr_8B_{20}$ (x=10, 15, and 20 at. %) were synthesized by single-roller melt-spinning. The measurement of coercivity, $H_c$, reveals the soft magnetic behavior of investigated alloys. The value of $H_c$ increases from 23 A/m for alloy with x=10 at. % up to 32 A/m for alloy with x=20 at. %. Further it was found that crystallization temperature of as-quenched alloys slightly varies with iron content and lays between 605 and 625°C. From the temperature dependence of magnetization it follows that partial substitution of cobalt by iron has positive influence on the Curie temperature of amorphous phase, $_cT^{am}$, which increases from 300°C up to 462°C for alloy with x=10 at. % and x=2 0 at. %, respectively.
    Źródło:
    Acta Physica Polonica A; 2008, 113, 1; 83-86
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Magnetic Properties of $NdFe_{0.9}Mn_{0.1}O_{3}$
    Autorzy:
    Zentková, M.
    Lazúrová, J.
    Kováč, J.
    Mihalik, M.
    Briančin, J.
    Fitta, M.
    Kusigerski, V.
    Powiązania:
    https://bibliotekanauki.pl/articles/1371226.pdf
    Data publikacji:
    2014-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.50.-y
    75.47.Lx
    75.30.-m
    75.30.Kz
    75.30.Et
    75.30.Cr
    Opis:
    In our paper we study effect of Mn for Fe substitution on magnetic properties of $NdFe_{x-1}Mn_{x}O_{3}$ compounds for x=0 and 0.1, which have been grown by the OFZ technique. The Néel temperature decreases from $T_{N1}$=691 K to $T_{N1}$=621 K, and the anomaly in AC susceptibility, related to spin reorientation, vanishes with Mn substitution. Low temperature heat capacity measurement for sample with x=0.1 revealed that substitution of Mn for Fe shifts a Schottky-type anomaly at $T_{sh}$ to higher temperatures. Another anomaly is generated by doping at $T_{max}$=11 K. The anomaly is smeared out by magnetic field, confirming its magnetic origin.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 1; 306-307
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Viscosity Dependence of a Magnetic Fluid Nanoparticles Concentration
    Autorzy:
    Tóthová, J.
    Kováč, J.
    Kopčanský, P.
    Rajňák, M.
    Paulovičová, K.
    Timko, M.
    Józefczak, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1201929.pdf
    Data publikacji:
    2014-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    07.55.Jg
    75.50.Mm
    83.85.Jn
    Opis:
    In this work we have studied the effect of temperature on the viscosity of magnetic fluids (MFs) based on the transformer oil ITO 100. The volume concentration of suspended magnetic particles (MPs) changed from 0.25 to 1%. Rheological characterization of MFs was performed using a vibroviscometer at working frequency of 30 Hz. The temperature dependence of the viscosity was measured in the temperature range from 20 up to 50 °C. The magnetization of different concentrations of MPs in MFs was determined by using the vibrating sample magnetometer.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 1; 278-279
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Magnetic Properties and Sorption Activity of Mechanically Activated Magnetite $Fe_3O_4$
    Autorzy:
    Baláž, P.
    Timko, M.
    Kováč, J.
    Bujňáková, Z.
    Ďurišin, J.
    Myndyk, M.
    Šepelák, V.
    Powiązania:
    https://bibliotekanauki.pl/articles/1535173.pdf
    Data publikacji:
    2010-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.60.Ej
    61.05.cp
    76.80.+y
    Opis:
    It is known that the action of mechanical forces on solids (mechanical activation and/or mechanochemistry) leads to changes of their properties and reactivity. We have studied the physico-chemical and sorption properties of magnetite $Fe_3O_4$ (Kiruna, Sweden) mechanically activated in a planetary mill. Several methods such as X-ray diffractometry, Mössbauer spectroscopy, magnetometry, specific surface area measurement as well as arsenic sorption tests have been applied. By X-ray diffractometry strong amorphisation of magnetite has been evidenced. In parallel, specific surface area increased from 0.1 $m^2//g$ for the reference (non-milled) sample to the values 0.5-6.1 $m^2//g$ for milled samples. The Mössbauer spectrum of the reference sample is well fitted with two subspectra corresponding to tetrahedrally (A) and octahedrally (B) coordinated iron cations in the spinel structure of $Fe_3O_4$. In mechanically activated samples (B)-site subspectrum becomes asymmetric, while (A)-site spectrum remains more or less unchanged. The more covalent character of the Fe(A)-O bond compared to the Fe(B)-O bond can explain qualitatively why the spin-density transfer from (A) to (B) in the spinel structure is more effective than vice versa. The value of the saturation magnetization at room temperature was 67.4 ≈ 43.6 emu/g which is significantly lower than that of the bulk particles 92 emu/g. This reduction may be attributed to the surface disorder or spin canting at the particle surface. During the milling process the coercivity value increases from 150 Oe up to 460 Oe with milling time. This increase can be related to the fact that magnetic anisotropy may increase when particle size decreases. The sorption activity of $Fe_3O_4$ was enhanced as a consequence of its disordering: 88% of $As^{3+}$ was captured for the mechanically activated sample in comparison with 0% for the non-milled one.
    Źródło:
    Acta Physica Polonica A; 2010, 118, 5; 1005-1007
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of AlN Buffer Layer Deposition Temperature οn Properties of GaN HVPE Layers
    Autorzy:
    Prażmowska, J.
    Korbutowicz, R.
    Wośko, M.
    Paszkiewicz, R.
    Kovač, J.
    Srnanek, R.
    Tłaczała, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1807541.pdf
    Data publikacji:
    2009-12
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    81.10.Bk
    81.15.Gh
    81.15.Kk
    Opis:
    Gallium nitride layers were deposited on AlN and double layer (AlN/AlGaN) buffers grown at various temperatures on $Al_{2}O_{3}$. Stress in layers was evaluated based on the Raman scattering and photoluminescence measurements. The obtained values were less than 1 GPa.
    Źródło:
    Acta Physica Polonica A; 2009, 116, S; S-123-S-125
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Magnetic Properties of Milled and Thermal Relaxed YBa$\text{}_{2}$ (Cu$\text{}_{1-x}$Fe$\text{}_{x}$)$\text{}_{3}$O$\text{}_{y}$
    Autorzy:
    Timko, M.
    Kováč, J.
    Sargánková, I.
    Zentková, M.
    Mihalik, M.
    Maťaš, S.
    Čiasnohová, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1955517.pdf
    Data publikacji:
    1997-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    74.90.+n
    74.10.+v
    74.70.-b
    Opis:
    The influence of the mechanical milling and subsequent thermal relaxation on magnetic and superconducting behaviour of YBa$\text{}_{2}$(Cu$\text{}_{1-x}$Fe $\text{}_{x}$)$\text{}_{3}$O$\text{}_{y}$ system has been studied. Two methods of heat treatment were used: Set I - slow cooling from 980°C in flowing O$\text{}_{2}$ and Set II - reducing at 770°C in flowing Ar$\text{}_{2}$ followed by reoxidation in flowing O$\text{}_{2}$ below 400°C. The transition to superconductivity, diamagnetic response, critical current density and the effective magnetic moment in the normal state have been estimated. Our measurements indicate that the reducing atmosphere preparation is less detrimental on superconducting properties. The results are discussed in terms of occupancy Cu sites by Fe and redistribution of oxygen atoms.
    Źródło:
    Acta Physica Polonica A; 1997, 91, 2; 355-358
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of Mn doping on magnetic and structural properties of Co₂FeSi Heusler alloy
    Autorzy:
    Galdun, L.
    Ryba, T.
    Kováč, J.
    Prida, V.
    Hernando, B.
    Vargová, Z.
    Varga, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/1054765.pdf
    Data publikacji:
    2017-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.20.Be
    72.20.Lp
    Opis:
    We have studied the effect of Mn doping on structural and magnetic properties of Co₂FeSi Heusler alloy. Co₂FeSi, Co₂Mn_{0.25}Fe_{0.75}Si and Co₂Mn_{0.5}Fe_{0.5}Si alloys were prepared by melt spinning technique which offers fast and simple production of large amount of materials in a single production step. The rapid quenching method provides an opportunity to prepare Heusler alloys with highly ordered L2₁ structure confirmed by X-ray analysis in all the samples. Magnetic measurements revealed high Curie temperatures (>1000 K) and well defined easy magnetization plane parallel with the ribbon plane. Those attributes predispose given samples for applications in spintronics.
    Źródło:
    Acta Physica Polonica A; 2017, 131, 4; 866-868
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Ferroelastic Phase Transition in a Layered Bismuth Oxychloride Single Crystals
    Autorzy:
    Bunda, V.
    Bunda, S.
    Vashchuk, F.
    Feher, A.
    Kajňaková, M.
    Kováč, J.
    Syrkin, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/1535538.pdf
    Data publikacji:
    2010-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.K-
    81.30.-t
    65.40.-b
    Opis:
    We report the results of low-temperature specific-heat, magnetization, and X-ray diffraction measurements on a bismuth oxyhalide (BiOCl) single crystal. We conclude that BiOCl in temperature region 150-230 K shows "antiferroelastic-paraelectric" phase transitions at critical temperatures $T_{c1}$ = 167.5 K and $T_{c2}$ = 214.6 K, respectively.
    Źródło:
    Acta Physica Polonica A; 2010, 118, 5; 1069-1070
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Physical Properties of Magnetite Nanoparticles Covered by 11-Mercaptoundecanoic Acid
    Autorzy:
    Timko, M.
    Kopčanský, P.
    Antalik, M.
    Simsikova, M.
    Valusova, E.
    Molcan, M.
    Kováč, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1429127.pdf
    Data publikacji:
    2012-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    47.65.Cb
    85.70.-w
    75.30.Cr
    75.47.Lx
    Opis:
    We have investigated the magnetic behavior of magnetite nanoparticles covered by the 11-mercaptoundecanoic acid around magnetite core prepared by a standard co-precipitation method. The particles show superparamagnetic behavior at room temperature, with transition to a blocked state at blocking temperature 91 K estimated from zero field cooled and field cooled at 500 Oe experiment. The hysteresis loop measured at 293 K showed magnetization 32.8 emu/g at 50 kOe without any coercivity. The mean particle size (7.1 nm) was determined by fitting a magnetization curve obtained at 295 K assuming a log-normal size distribution.
    Źródło:
    Acta Physica Polonica A; 2012, 121, 5-6; 1321-1323
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Structure and Properties of Soft-Magnetic Amorphous Bilayer Ribbons
    Autorzy:
    Švec, P.
    Mat'ko, I.
    Marcin, J.
    Kováč, J.
    Vlasák, G.
    Janičkovič, D.
    Škorvánek, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/1534100.pdf
    Data publikacji:
    2010-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    68.37.Hk
    68.37.Lp
    Opis:
    Rapidly quenched bilayers consisting of Fe-Si-B and Co-Si-B layers have been prepared by planar flow casting from a single crucible with two nozzles. Temperature dependences of electrical resistivity, dilatation and magnetization have been investigated in the amorphous state and during crystallization of both layers. Preliminary studies of the structure of the layers and of the interlayer have been performed by X-ray diffraction, cross-sectional electron microscopy and microanalysis. From the results it seems evident that the process of connection of the two layers during preparation takes place by solidification with only a small extent of mutual interdiffusion of component atoms localized to a narrow well-defined interface, leading to mechanically solid connection between the two layers. The effect of combined presence of two different soft magnetic alloys on the overall magnetic properties is discussed with respect to potential applications of such materials.
    Źródło:
    Acta Physica Polonica A; 2010, 118, 5; 832-834
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Magnetic and Structural Characterization of Nickel and Iron Based Heusler Ribbons Ni₂FeZ (Z = In, Sn, Sb)
    Autorzy:
    Frol'ová, L.
    Ryba, T.
    Vargová, Z.
    Komanický, V.
    Kováč, J.
    Gyepes, R.
    Varga, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/1032228.pdf
    Data publikacji:
    2017-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.20.En
    75.30.Gw
    Opis:
    Comparison of structural, chemical, and magnetic properties of Ni₂FeZ (Z = In, Sn, Sb) Heusler ribbons produced by melt-spinning method is presented. The aim of work was to prepare the Heusler alloys with the appropriate chemical composition in a single step without additional thermal treatment. Scanning electron microscopy analysis revealed polycrystalline structure of all samples. It is shown that correct L2₁ structure of Ni₂FeSb can be obtained in a single production step. On the other hand, no Heusler L2₁ phase (nor its variants) occur in Ni₂FeSn alloy. Additionally, magnetic characterization revealed high Curie temperatures of the Heusler phases (above 600 K for Ni₂FeSb and 800 K for Ni₂FeIn).
    Źródło:
    Acta Physica Polonica A; 2017, 131, 4; 735-737
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Mechanochemical Reduction of Chalcopyrite CuFeS₂: Changes in Composition and Magnetic Properties
    Autorzy:
    Baláž, P.
    Zorkovská, A.
    Baláž, M.
    Kováč, J.
    Tešinský, M.
    Osserov, T.
    Guseynova, G.
    Ketegenov, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/1032642.pdf
    Data publikacji:
    2017-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.50.Pp
    81.05.Hd
    Opis:
    High-energy milling of sulphides with a reactive metal in so-called mechanochemical reduction mode can lead to products in nanorange and to composition which simplifies the following metallurgical processing. Chalcopyrite CuFeS₂, a ternary semiconductor with antiferromagnetic properties represents promising candidate as an advanced material for use in inexpensive nanoelectronics (solar cells, magnetic area), as well as copper ore source in metallurgical operations. In this work, the process of mechanochemical reduction of chalcopyrite with elemental iron is studied. The composition and properties of nanopowder prepared by high-energy milling were analyzed by X-ray diffraction and magnetic measurements. Most of the reaction takes place during 30 min with chalcocite Cu₂S and troilite FeS as the only reaction products. The magnetic investigations reveal significant increase of saturation magnetization as a result of milling. Unlike the conventional high-temperature reduction of chalcopyrite, the mechanochemical reduction is fast and ambient temperature and atmospheric pressure are sufficient for its propagation.
    Źródło:
    Acta Physica Polonica A; 2017, 131, 4; 1165-1167
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Time Dependent Changes in Ag Doped YBCO Superconductors
    Autorzy:
    Volochová, D.
    Antal, V.
    Diko, P.
    Šefčiková, M.
    Zmorayová, K.
    Kováč, J.
    Weber, H.
    Chaud, X.
    Powiązania:
    https://bibliotekanauki.pl/articles/1535451.pdf
    Data publikacji:
    2010-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    74.25.Ha
    74.25.Sv
    74.62.Bf
    74.62.Dh
    74.62.Fj
    Opis:
    Magnetization measurements at 77 K were conducted on the single-crystalline samples of YBCO superconductor doped with Ag prepared by the top-seeded melt-growth process. The single-grain samples had a nominal composition $Y_{1.5}Ba_2(Cu,Ag)_3O_{y}$. Magnetization measurements on the samples, oxygenated by two different processes: by standard oxygenation and by high pressure oxygenation, repeated after 24 months, revealed time dependent changes in magnetization behaviour and critical transition temperatures, T_{c}, which could be associated with redistribution of oxygen vacancies and their interaction with Ag dopant atoms.
    Źródło:
    Acta Physica Polonica A; 2010, 118, 5; 1047-1048
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of Sm and Yb Pollution on Superconducting Properties of YBCO Bulk Superconductors
    Autorzy:
    Volochová, D.
    Jurek, K.
    Radušovská, M.
    Piovarči, S.
    Antal, V.
    Kováč, J.
    Jirsa, M.
    Diko, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1371573.pdf
    Data publikacji:
    2014-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    74.60.Bf
    74.72.-h
    81.40.Rs
    74.25.Ha
    74.81.Bd
    74.25.Op
    Opis:
    $YBa_{2}Cu_{3}O_{7-δ }$ (YBCO, Y-123) bulk superconductors with a nominal composition $Y_{1.5}Ba_{2}Cu_{3}O_{x}$ and 1 wt% $CeO_{2}$ addition were prepared by the Top Seeded Melt Growth (TSMG) process. Small single-crystalline pieces, cut from the $SmBa_{2}Cu_{3}O_{y}$ (Sm-123) bulk, were used for seeding of epitaxial growth. Wavelength-dispersive spectrometry (WDS) confirmed the presence of 0.1 wt% Sm from the seed and 0.25 wt% Yb from the substrate, practically in the whole sample volume. The influence of this Sm and Yb contamination on superconducting properties of grown bulk materials is reported.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 1; 358-359
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Mechanochemically Synthesized Nanocrystalline $Sb_2S_3$ Particles
    Autorzy:
    Dutková, E.
    Sayagués, M.
    Real, C.
    Zorkovská, A.
    Baláž, P.
    Šatka, A.
    Kováč, J.
    Ficeriová, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1375343.pdf
    Data publikacji:
    2014-10
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    81.05.Hd
    81.07.Bc
    81.20.Wk
    Opis:
    Nanocrystalline $Sb_2S_3$ particles have been synthesized from Sb and S powders by high-energy milling in a planetary mill using argon protective atmosphere. X-ray diffraction, particle size analysis, scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, electron diffraction, high resolution transmission electron microscopy, UV-VIS, and differential scanning calorimetry methods for characterization of the prepared particles were applied. The powder X-ray diffraction pattern shows that $Sb_2S_3$ nanocrystals belong to the orthorhombic phase with calculated crystallite size of about 36 nm. The nanocrystalline $Sb_2S_3$ particles are constituted by randomly distributed crystalline nanodomains (20 nm) and then these particles are forming aggregates. The monomodal distribution of $Sb_2S_3$ particles with the average hydrodynamic parameter 210 nm was obtained. The quantification of energy dispersive X-ray spectroscopy analysis peaks give an atomic ratio of 2:3 for Sb:S. The optical band gap determined from the absorption spectrum is 4.9 eV, indicating a considerable blue shift relative to the bulk $Sb_2S_3$. Differential scanning calorimetry curves exhibit a broad exothermic peak between 200 and 300°C, suggesting recovery processes. This interpretation is supported by X-ray diffraction measurements that indicate a 23-fold increase of the crystallite size to about 827 nm as a consequence of application of high temperature process. The controlled mechanochemical synthesis of $Sb_2S_3$ nanoparticles at ambient temperature and atmospheric pressure remains a great challenge.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 4; 943-946
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    AC Magnetic Susceptibility of Ferrofluids Exposed to an External Electric Field
    Autorzy:
    Rajňák, M.
    Dolník, B.
    Kováč, J.
    Paulovičová, K.
    Mitróová, Z.
    Kurimský, J.
    Cimbala, R.
    Kopčanský, P.
    Timko, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1032260.pdf
    Data publikacji:
    2017-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    47.65.Cb
    75.75.Fk
    75.78.-n
    83.60.Np
    Opis:
    It is known that ferrofluid superparamagnetic nanoparticles response to external magnetic fields, often resulting in the formation of elongated clusters along the field. This has a notable impact on dielectric properties of ferrofluids. Here we report on indications of a contrary effect when the magnetic susceptibility of ferrofluids based on transformer oil is influenced by an external electric field. This effect is associated with structural changes in the ferrofluids induced by the external electric fields. Particularly, we focus on a steady state electric field effect, which gives rise to forces acting on the magnetite nanoparticles, leading to the formation of aggregates. In this condition we have measured the ferrofluid AC magnetic susceptibility in parallel and perpendicular configuration of magnetic and electric fields at room temperature. The measurements in both configurations yielded a noticeable decrease in the real susceptibility values with increasing electric field intensity. The result is believed to be caused by the reduction in the total magnetic moment of the ferrofluid. This can be a consequence of the superspin interactions in the aggregates, minimizing the aggregate's energy. Finally, we highlight the necessity of NMR and small angle scattering of polarized neutrons investigations in order to obtain exact information on the magnetic structure induced by the electric forces.
    Źródło:
    Acta Physica Polonica A; 2017, 131, 4; 887-889
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Elimination of Magnetic Nanoparticles with Various Surface Modifications from the Bloodstream in vivo
    Autorzy:
    Tomasovicova, N.
    Khmara, I.
    Koneracka, M.
    Zavisova, V.
    Kubovcikova, M.
    Antal, I.
    Kovac, J.
    Muckova, M.
    Kopcansky, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1032816.pdf
    Data publikacji:
    2017-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.50.Gg
    75.50.Tt
    87.85.jj
    Opis:
    The magnetic nanoparticles with the core diameter 10 nm stabilized by sodium oleate and bovine serum albumin in phosphate buffer have been modified by different biocompatible substances such as poly(ethylene glycol) (PEG), dextran (DEX), and polyvinylpyrrolidone (PVP). Prepared biocompatible magnetic fluids were characterized to obtain the particle size distribution using scanning electron microscopy and the dynamic light scattering method. To study the elimination of different modified magnetic nanoparticles from bloodstream, the biocompatible samples were applied intravenously to the mice bloodstream with further blood specimens collecting in given time intervals. Magnetic moment of the lyophilized blood samples was measured by SQUID magnetometer. Time dependence of magnetic moment of magnetic nanoparticles and magnetic nanoparticles modified by DEX, PEG and PVP normalized to the Fe₃O₄ showed that the circulation time of magnetic nanoparticles in the bloodstream depends on the substance used for modification. The unmodified magnetic nanoparticles were trapped by reticuloendothelial system within 1 h while magnetic nanoparticles modified by DEX, PEG and PVP circulated in blood up to 3 h.
    Źródło:
    Acta Physica Polonica A; 2017, 131, 4; 1159-1161
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Structural Characterization of Ni-Ti-Zr Metallic Glass
    Autorzy:
    Katuna, Yu.
    Lisnichuk, M.
    Saksl, K.
    Girman, V.
    Gamcová, J.
    Balga, D.
    Ďurišin, M.
    Kováč, J.
    Sovák, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1032136.pdf
    Data publikacji:
    2017-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.50.Kj
    68.37.Ma
    68.37.Lp
    Opis:
    Metallic glasses, in contrast to its crystalline counterparts, exhibit unique mechanical and structural properties, which make them attractive for practical applications. Especially Ni-Ti-Zr metallic glass is a promising alloy for micromechanical systems because of its known shape memory properties. Shape memory effect is connected with structural phase transformation. In this paper, the ambient-temperature-structure of Ni-Ti-Zr metallic glass is investigated using transmission electron microscopy and synchrotron X-ray diffraction, the surface and chemical analysis is documented using scanning electron microscopy. Thermal stability of the alloy has been determined using differential scanning calorimetry.
    Źródło:
    Acta Physica Polonica A; 2017, 131, 4; 750-752
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Differentiation of Native and Reconstructed Ferritin using the MRI Gradient Echo Pulse Sequence
    Autorzy:
    Balejcikova, L.
    Strbak, O.
    Baciak, L.
    Kovac, J.
    Masarova, M.
    Krafcik, A.
    Kopcansky, P.
    Dobrota, D.
    Frollo, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/1032829.pdf
    Data publikacji:
    2017-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.60.Ej
    83.85.Fg
    87.61.-c
    87.64.Cc
    87.85.jf
    Opis:
    Ferritin is a biological iron storage biomacromolecule, consisting of a spherical protein shell (apoferritin) and mineral iron core. It plays a crucial role in the pathological processes of disrupted iron homeostasis followed by iron accumulation, linked with various disorders (e.g. neuroinflammation, neurodegeneration, cirrhosis, cancer, etc.) In vitro reconstructed ferritin, with the assistance of a non-invasive magnetic resonance imaging technique, has the potential to become a suitable biomarker of these pathological processes. Through gradient echo pulse sequencing, we were able to clearly distinguish between native (physiological) and reconstructed/iron-overloaded (pathological) ferritin, which can serve as a starting point for the development of a method for their differentiation. Such method is necessary for the early diagnosis of iron-based diseases.
    Źródło:
    Acta Physica Polonica A; 2017, 131, 4; 1093-1095
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Influence of Morphology on Magnetic Properties of Magnetosomes
    Autorzy:
    Hashim, A.
    Molčan, M.
    Kovač, J.
    Varchulová, Z.
    Gojzewski, H.
    Makowski, M.
    Kopčansky, P.
    Tomori, Z.
    Timko, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1428653.pdf
    Data publikacji:
    2012-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    47.65.Cb
    51.60.+a
    75.30.Gw
    75.50.Tt
    75.60.Nt
    75.60.Ej
    Opis:
    Cultivation process was changed three times. The culture medium was enriched by more amount ferric quinate (FQ magnetosomes sample) and more amounts Wolfe's vitamin solution (WVS magnetosomes sample) comparing to normal culture medium (NP magnetosomes sample). NP sample of magnetosomes shows zero coercivity and behaves superparamagnetically. The increase of coercivity (6.5 Oe for WVS and 20 Oe for FQ) may be caused by higher value of shape anisotropy and reveals stronger magnetic correlations between particles of magnetite chains.
    Źródło:
    Acta Physica Polonica A; 2012, 121, 5-6; 1250-1252
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Radiation Stability of the BSA Modified Biocompatible Magnetic Fluid
    Autorzy:
    Tomašovičová, N.
    Haysak, I.
    Kováč, J.
    Kubovčíková, M.
    Závišová, V.
    Timko, M.
    Okunev, A.
    Zorkovská, A.
    Kopčanský, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1368667.pdf
    Data publikacji:
    2014-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.50.Mm
    61.30.Gd
    64.70.Md
    Opis:
    The aim of the presented work was to investigate the stability of biocompatible magnetic fluid, i.e. water-based magnetic fluid containing magnetite nanoparticles stabilized by surfactant sodium oleate and modified by bovine serum albumin (BSA) after electron irradiation. Samples with the same concentration of $Fe_{3}O_{4}$ but different mass ratio BSA/$Fe_{3}O_{4}$ (w/w=0.25, 1.0 and 2.5) were studied. The electron irradiation caused about 10% reduction of the saturation magnetization in the samples with w/w BSA/$Fe_{3}O_{4}$ ratio of 0.25 and less than 5% in the samples with w/w BSA/$Fe_{3}O_{4}$ ratio of 1 and 2.5.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 1; 262-263
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Anisotropy of the Electrical Resistivity and Thermal Expansion of Single Crystal DyNi$\text{}_{5}$
    Autorzy:
    Kačmarčiková, E.
    Reiffers, M.
    Mihálik, M.
    Kováč, J.
    Menovsky, A.
    Garcia Soldevilla, J.
    Señas Pariente, A.
    Goméz Sal, J. C.
    Powiązania:
    https://bibliotekanauki.pl/articles/2013656.pdf
    Data publikacji:
    2000-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    72.15.Eb
    65.70.+y
    71.70.Gm
    Opis:
    The results of the measurements of temperature dependence of the electrical resistivity ρ(T), thermal expansion L(T) and susceptibility χ(T) on single crystal DyNi$\text{}_{5}$ in the temperature range 4.2-300 K are reported. The maximum in ρ(T) at T$\text{}_{N}$=12.2 K was observed which corresponds to the transition to antiferromagnetically ordered state. Taking into account the Bloch-Grüneisen formula for electron-phonon contribution ρ$\text{}_{ph}$(T) to ρ(T) the anisotropic magnetic contribution ρ$\text{}_{mag}$(T) was determined. We also observed the anisotropic behaviour of L(T) at low temperatures.
    Źródło:
    Acta Physica Polonica A; 2000, 97, 5; 811-814
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Correlation between Magnetic and Structural Properties in Ni-Ti-Zr Metallic Glass
    Autorzy:
    Lisnichuk, M.
    Katuna, Yu.
    Saksl, K.
    Girman, V.
    Gamcová, J.
    Balga, D.
    Ďurišin, M.
    Kováč, J.
    Kollár, P.
    Sovák, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1032297.pdf
    Data publikacji:
    2017-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    07.85.Jy
    75.50.Kj
    61.43.Dq
    Opis:
    The Ni-Ti-Zr metallic glasses are due to their known shape memory properties promising alloys e.g. for micromechanical applications. In this paper structure and structure stability of one particular alloy Ni₆₀Ti₂₅Zr₁₅ at.% were examined by means of X-ray diffraction and transmission electron microscopy while magnetic properties were ascertained by vibrating-sample magnetometer with maximal applied field of 100 kA/m in the temperature range of 300-1073 K.
    Źródło:
    Acta Physica Polonica A; 2017, 131, 4; 741-743
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Magnetic Properties of Magnetite Formed by Biomineralization and Chemical Synthesis
    Autorzy:
    Timko, M.
    Džarová, A.
    Kopčanský, P.
    Závišová, V.
    Koneracká, M.
    Kováč, J.
    Šprincová, A.
    Vaclavíková, M.
    Ivaničová, L.
    Vávra, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/1813922.pdf
    Data publikacji:
    2008-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.75.+a
    47.65.Cb
    87.83.+a
    Opis:
    In this work, the magnetic properties of biologically produced magnetite (magnetosomes) by biomineralization process were compared to those of chemically synthesized $Fe_3O_4$. The coercivity of 185 Oe in magnetosomes is connected with the fact that the mean diameter is larger than critical size for transition from superparamagnetic to ferromagnetic behavior. A sharp magnetic transition at 105 K (Verwey transition) is clearly present in magnetosomes while in opposite, this transition is missing in $Fe_3O_4$.
    Źródło:
    Acta Physica Polonica A; 2008, 113, 1; 573-576
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Characterization of Magnetosomes After Exposure to the Effect of the Sonication and Ultracentrifugation
    Autorzy:
    Molčan, M.
    Hashim, A.
    Kováč, J.
    Rajňák, M.
    Kopčanský, P.
    Makowski, M.
    Gojzewski, H.
    Molokáč, M.
    Hvizdák, L.
    Timko, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1368025.pdf
    Data publikacji:
    2014-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    81.07.-b
    75.60.-d
    87.50.Y-
    68.37.-d
    Opis:
    Magnetosomes are intracellular organelles of widespread aquatic microorganisms called Magnetotactic bacteria. At present they are under investigation especially in biomedical applications. This ability depends on the presence of intracellular magnetosomes which are composed of two parts: first, nanometer-sized magnetite $(Fe_{3}O_{4})$ or greigite $(Fe_{3}S_{4})$ crystals (magnetosome crystal), depending on the bacterial species; and second, the bilayer membrane surrounding the crystal (magnetosome membrane). The magnetosomes were prepared by biomineralization process of magnetotactic bacteria Magnetospirillum Magnetotacticum sp. AMB-1. The isolated magnetosome chains (sample M) were centrifugated at speed of 100000 rpm for 4 hours (sample UM) and sonicated at power of 120 W for 3 hours (sample SM), respectively. The prepared suspensions were investigated with respect to morphological, structural and magnetic properties. The results from scanning electron microscopy showed that isolated chains of magnetosomes were partially broken to smaller ones after ultracentrifugation. On the other hand the application of the sonication process caused the formation of individual magnetosomes (unordered in chain). These results were confirmed by coercivity and magnetization saturation measurements.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 1; 198-199
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Magnetic Properties of Biocompatible Magnetic Fluid after Electron Irradiation
    Autorzy:
    Tomašovičová, N.
    Haysak, I.
    Koneracká, M.
    Kováč, J.
    Timko, M.
    Závišová, V.
    Okunev, A.
    Parlag, A.
    Fradkin, A.
    Sakhno, V.
    Kopčanský, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1429089.pdf
    Data publikacji:
    2012-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.50.Mm
    61.80.Fe
    61.82.Rx
    Opis:
    The magnetic particles in the water-based magnetic fluids were sterically stabilized by natrium oleate to prevent their agglomeration and consequently the adsorption of poly-ethylene-glycol (PEG) was carried out to improve the biocompatibility of the magnetic particles. Two sets of samples were prepared. The first set of the samples was with different molar weight of PEG (Mw = 400, 1000, 10000 and 20000) at the constant weight ratio of PEG/$Fe_3O_4$ = 0.25 and the second one was with different weight ratio of PEG/$Fe_3O_4$ and constant molar weight of PEG (Mw = 1000). The samples were irradiated with 20 Gy. The same reduction of saturated magnetization (about 10%) after electron irradiation with 20 Gy was observed for all prepared samples.
    Źródło:
    Acta Physica Polonica A; 2012, 121, 5-6; 1302-1304
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    AP-MOVPE Technology and Characterization of InGaAsN p-i-n Subcell for InGaAsN/GaAs Tandem Solar Cell
    Autorzy:
    Dawidowski, W.
    Ściana, B.
    Zborowska-Lindert, I.
    Mikolásek, M.
    Latkowska, M.
    Radziewicz, D.
    Pucicki, D.
    Bielak, K.
    Badura, M.
    Kováč, J.
    Tłaczała, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/226630.pdf
    Data publikacji:
    2014
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    dilute nitrides
    AP MOVPE
    subcell
    tandem solar cell
    J-V characteristics
    Opis:
    Tandem (two p-n junctions connected by tunnel junction) and multijunction solar cells (MJSCs) based on AIIIBV semiconductor compounds and alloys are the most effective photovoltaic devices. Record efficiency of the MJSCs exceeds 44% under concentrated sunlight. Individual subcells connected in series by tunnel junctions are crucial components of these devices. In this paper we present atmospheric pressure metal organic vapour phase epitaxy (AP-MOVPE) of InGaAsN based subcell for InGaAsN/GaAs tandem solar cell. The parameters of epitaxial structure (optical and electrical), fabrication process of the test solar cell devices and current-voltage (J-V) characteristics are presented and discussed.
    Źródło:
    International Journal of Electronics and Telecommunications; 2014, 60, 2; 151-156
    2300-1933
    Pojawia się w:
    International Journal of Electronics and Telecommunications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Characterization of $Fe_3O_4$ Magnetic Nanoparticles Modified with Dextran and Investigation of Their Interaction with Protein Amyloid Aggregates
    Autorzy:
    Koneracká, M.
    Antošová, A.
    Závišová, V.
    Lancz, G.
    Gažová, Z.
    Šipošová, K.
    Juríková, A.
    Csach, K.
    Kováč, J.
    Tomašovičová, N.
    Fabián, M.
    Kopčanský, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1535048.pdf
    Data publikacji:
    2010-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.50.Mm
    87.14.em
    87.19.xr
    Opis:
    Functionalised magnetic nanoparticles composed of $Fe_3O_4$ particles stabilised by sodium oleate and subsequently modified with dextran (MFDEX) were prepared by the co-precipitation method. Their morphology and particle size distribution were observed by scanning electron microscopy and photon cross correlation spectroscopy. In order to confirm the modification of magnetite surface with dextran physical techniques, including infrared spectroscopy, thermal analysis, and magnetic measurement, were used. Finally, the effect of MFDEX on amyloid fibrillar aggregates of human insulin and hen egg white lysozyme, typical amyloidogenic proteins, was investigated. In vitro interaction of MFDEX with protein amyloid fibrils resulted into destruction of amyloid aggregates. The anti-amyloid activity makes MFDEX of potential interest as therapeutic agent against amyloid-related diseases.
    Źródło:
    Acta Physica Polonica A; 2010, 118, 5; 983-985
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Design of DC permanent magnet disc motor and improving its EMC
    Autorzy:
    Kovacova, I.
    Kanuch, J.
    Kovac, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/262741.pdf
    Data publikacji:
    2005
    Wydawca:
    Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie
    Tematy:
    electromagnetic compatibility
    disc motor
    electromagnetic field radiation
    Opis:
    The paper deals with construction design of DC permanent magnet disc motor by classical calculation method and its verifying by computer finite element simulation method. The paper deals also with the computer analysis of the electromagnetic compatibility (EMC) problems focused to the area of electrical machines, which can also disclose the startling facts concerning. A problem of interference between electric motor and surroundings space caused by electromagnetic field radiation is discussed too.
    Źródło:
    Electrical Power Quality and Utilisation. Journal; 2005, 11, 2; 23-39
    1896-4672
    Pojawia się w:
    Electrical Power Quality and Utilisation. Journal
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analiza oddziaływania między pojazdem a nawierzchnią dla celów klasyfikacji IRI w ramach słowackiego PMS
    An analysis of vehicle-road surface interaction for classifi cation of IRI in the frame of Slovak PMS
    Autorzy:
    Celko, J.
    Decky, M.
    Kovac, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/301414.pdf
    Data publikacji:
    2009
    Wydawca:
    Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
    Tematy:
    stan drogi
    nawierzchnia
    równość
    bezpieczeństwo
    droga
    niedogodności
    road serviceability
    pavement
    evenness
    road safety
    discomfort
    Opis:
    Równość jest jednym z podstawowych czynników jakości nawierzchni. Stanowi ona charakterystykę stanu drogi, jak również bezpieczeństwa na drodze i komfortu jazdy. Nierówności podłużne powodują niedogodności w ruchu drogowym i niebezpieczeństwo zmniejszenia oddziaływania między kołami a nawierzchnią. Wymienione aspekty zostały wzięte pod uwagę w analizie poziomów klasyfikacji w ramach Słowackiego PMS. Symulacje różnych warunków brzegowych podczas diagnostyki nawierzchni miały na celu przede wszystkim zbadanie wpływu nierówności na pojazd, a co za tym idzie, na komfort jazdy. Z drugiej strony, wpływ nierówności na oddziaływanie między nawierzchnią a kołem stanowił podstawowe kryterium oceny z punktu widzenia bezpieczeństwa. Przedmiotem artykułu jest obserwacja i ocena opisanych parametrów podczas przeprowadzonych symulacji i pomiarów eksperymentalnych. Do symulacji użyto dynamicznych charakterystyk prawdziwych pojazdów.
    Road evenness is one from basic factors of the pavement quality. It represents the characteristic of the road serviceability but also road safety and comfortable. The longitudinal unevenness causes the traffi c discomfort and danger of the wheel-pavement interaction decreasing. Listed aspects were taken into account for analyze of classifi cation levels in frame of the Slovak PMS. The simulations of different boundary conditions during pavement surface diagnostics were oriented above all to the response of unevenness to the vehicle and to the ride comfort consequently. On the other hand an effect of unevenness to interaction between surface and wheel was the basic criteria of evaluation from safety point of view. The paper is oriented to the observation and evaluation described parameters during realized simulations and experimental measurements. For simulations were used dynamic characteristics of real vehicles.
    Źródło:
    Eksploatacja i Niezawodność; 2009, 1; 15-21
    1507-2711
    Pojawia się w:
    Eksploatacja i Niezawodność
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of Thermal Processing in High Magnetic Field on Soft Magnetic Properties and Crystallographic Texture of Non-Oriented Fe-Si Steels
    Autorzy:
    Petryshynets, I.
    Kováč, F.
    Marcin, J.
    Škorvánek, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/1032640.pdf
    Data publikacji:
    2017-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.50.Kj
    61.72.-y
    68.55.jm
    75.60.Nt
    75.50.Vv
    Opis:
    In this work, we report on the effects of high static magnetic field on the formation of desirable crystallographic orientation of grains ("rotating" cube) during the primary recrystallization of non-oriented steels. Vacuum degassed non-oriented steel with the silicon content about 1 wt% was taken from industrial line after final cold rolling with 80% of deformation and then it was subjected to the laboratory annealing at temperature of primary recrystallization. Whole annealing process was carried with and without the applied external magnetic field of 14 T. The analysis of crystallographic orientation of experimental material was studied by electron backscattered diffraction technique. The microstructural and textural observations have shown a small difference in average grain size between samples annealed with and without magnetic field as well as increase of the "rotating" Cube component and decrease of the intensity of deformation texture by application of magnetic field. The magnetic measurements show that the coercivity value of the sample annealed in the magnetic field of 14 T can be reduced by approximately 3% in comparison with sample annealed under the zero field conditions.
    Źródło:
    Acta Physica Polonica A; 2017, 131, 4; 783-785
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Application of the statistical control of the production processes in organisation
    Zastosowanie statystycznej kontroli w zakresie procesów produkcyjnych w organizacji
    Autorzy:
    Žarnovský, J.
    Drlička, R.
    Kováč, I.
    Petruš, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/409896.pdf
    Data publikacji:
    2014
    Wydawca:
    STE GROUP
    Tematy:
    statistical process control
    production organization
    regulation processes
    process capability
    statistical control
    control chart
    statystyczna kontrola procesu
    organizacja produkcji
    procesy regulacyjne
    zdolności procesu
    kontrola statystyczna
    wykres sterowania
    Opis:
    All recent experiences confirm the fact that the main tasks of quality management are guaranteed only with the high skilled employees. Employees are responsible for the production plan and development, services and processes. The series of standards called ISO 9000 help to establish quality management in organization. Usage of the quality management with statistical process control is also very important for the company. Companies are spending all human, material and financial resources to improve quality management. The objective of the paper is to outline the statistical process control in production company Finalcast Ltd. Žiar nad Hronom.
    Wszystkie ostatnie doświadczenia potwierdzają fakt, że główne zadania zarządzania jakością są gwarantowane tylko z wysoko wykwalifikowanymi pracownikami. Pracownicy są odpowiedzialni za plan produkcji i rozwoju, usług i procesów. Seria norm ISO 9000 jest pomocna w celu ustalenia zarządzania jakością w organizacji. Korzystanie w zarządzaniu jakością ze statystycznej kontroli procesu jest również bardzo ważne dla firmy. Firmy wykorzystują wszystkie zasoby ludzkie, materialne i finansowe w celu poprawy jakości zarządzania. Celem pracy jest określenie statystycznego sterowania procesem w produkcji firmy Finalcast Ltd. Žiar nad Hronom.
    Źródło:
    Management Systems in Production Engineering; 2014, 3 (15); 135-139
    2299-0461
    Pojawia się w:
    Management Systems in Production Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of Microstructure Evolution on the Coercive Forces in Low Silicon Non-Oriented Steels
    Autorzy:
    Petryshynets, I.
    Kovac, F.
    Stoyka, V.
    Boruta, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1535233.pdf
    Data publikacji:
    2010-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.20.En
    74.25.Ha
    75.50.Bb
    75.50.Gg
    Opis:
    The magnetic properties and their dependence on the peculiarity of microstructure in low silicon non-oriented electrotechnical steels were studied in the present work. The estimation of dc magnetic properties of electrical steels was carried out by measurements of coercive forces. It was shown that the coercive force change in silicon steels is dependent on change of average grain size, crystallographic texture and homogeneity of microstructure of the materials. It was revealed that the steels possessing columnar or huge grained microstructure had the lowest measured values of coercive forces. The materials with such microstructure are characterized by a domination of (100) 〈0vw〉 crystallographic orientation.
    Źródło:
    Acta Physica Polonica A; 2010, 118, 5; 1013-1014
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Improved Processing Technique for Preparation of Non-Oriented Electrical Steels with Low Coercivity
    Autorzy:
    Petryshynets, I.
    Kovac, F.
    Marcin, J.
    Škorvanek, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/1367959.pdf
    Data publikacji:
    2014-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.72.-y
    61.72.Cc
    81.40.Ef
    75.50.Vv
    Opis:
    In order to improve soft magnetic properties of vacuum degassed NO steels, an adjusted temper rolling process for development of particular textures {100}<0vw> was used. The main idea here relies on a deformation-induced grain growth, which promotes preferable formation of the grains with desired orientation. Two vacuum degassed NO steels were chosen as an experimental material. In both cases, a coarse or columnar grained microstructure, with pronounced intensity of cube and Goss texture components, was achieved during a continuous final annealing. The obtained microstructure leads to a significant decrease of coercivity, measured in DC magnetic field. The coercivity of steel with silicon content 2.4 wt.% decreased from 42 A/m to 17 A/m. Even more remarkable improvement of the soft magnetic properties was observed for the steel with Si 0.6 wt.%, where the coercivity value dropped from 68 A/m to 12.7 A/m.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 1; 182-183
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Distribution of Diazinon and Selenium in Various Tissues after Single and Common Intraperitoneal Administration
    Dystrybucja diazinonu i selenu w wybranych tkankach po pojedynczym podaniu dootrzewnowym
    Autorzy:
    Šiška, B.
    Toman, R.
    Golian, J.
    Bošiak, M.
    Kovac, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/388389.pdf
    Data publikacji:
    2009
    Wydawca:
    Towarzystwo Chemii i Inżynierii Ekologicznej
    Tematy:
    dianizon
    selen
    wątroba
    nerki
    mięśnie
    tłuszcz
    podanie dootrzewnowe
    diazinon
    selenium
    liver
    kidney
    muscle
    fat
    intraperitoneal administration
    Opis:
    The aim of this study was to evaluate the distribution of diazinon and selenium in various tissues of laboratory rats after single and common intraperitoneal administration. Rats in the age of 135 days were randomly divided into 4 groups. Each group consisted of 10 males. Animals in the first group were administrated with diazinon 20 mg o kg-1 body weight intraperitoneally. Animals in the second group were administrated with selenium (Na2SeO3) 2 mg Se o kg-1 body weight intraperitoneally in physiological solution. Animals in the third group were given a mixture of diazinon 20 mg o kg-1 body weight and selenium 2 mg Se o kg-1 body weight intraperitoneally in physiological solution. The fourth group served as a control group and was administrated only with the physiological solution. 24 hours after the administration of tested substances, animals were sacrificed and samples of livers, kidneys, muscles and fat tissue were taken during the autopsy. The amount of diazinon in tissues was determined using gas chromatography with mass spectrometry. The amount of selenium was determined using atomic absorption spectrometry. We detected significant increase of selenium amount in livers, kidneys and muscles after single selenium administration and also after common administration of both substances. On the other hand we detected significant decrease of selenium amount in muscles and fat tissue after single diazinon administration. We also observed slight accumulation of diazinon amount in samples of kidneys and muscles and significant increase of diazinon in fat tissue after single diazinon administration and also after common administration of both substances.
    Celem pracy było określenie dystrybucji dianizonu i selenu w różnych tkankach szczurów laboratoryjnych po pojedynczym dootrzewnowym podaniu. Szczury w wieku 135 dni zostały losowo przyporządkowane do 4 grup. Każda grupa składała się z 10 samców. Zwierzętom z pierwszej grupy podano dootrzewnowo dianizon w dawce 20 mg o kg-1 masy ciała. Zwierzętom drugiej grupy podano dootrzewnowo selen w roztworze fizjologicznym (Na2SeO3) w dawce 2 Se mg o kg-1 masy ciała. Zwierzęta trzeciej grupy otrzymały dootrzewnowo mieszaninę dianizonu (20 mg o kg-1) i selenu (Na2SeO3 - 2 Se mg o kg-1) w roztworze fizjologicznym. Czwartą grupę stanowiły zwierzęta kontrolne, którym podano wyłącznie roztwór fizjologiczny. Po 24 godzinach od podania dianizonu i selenu zwierzęta uśmiercono, po czym pobrano próbki wątroby, nerek, mięśni i tkanki tłuszczowej. Poziom dianizonu w tkankach został zbadany przy użyciu chromatografii gazowej oraz spektrofotometrii masowej. Selen oznaczono metodą spektrofotometrii absorpcji atomowej. Stwierdzono istotny statystycznie wzrost poziomu selenu w wątrobie, nerkach i mięśniach po jednorazowym podaniu selenu, a także po podaniu mieszaniny selenu i dianizonu. Z drugiej strony odnotowano również istotny statystycznie spadek zawartości selenu w mięśniach i tkance tłuszczowej po jednorazowym podaniu dianizonu. Zaobserwowano także niewielki wzrost poziomu dianizonu w nerkach i mięśniach oraz istotny statystycznie wzrost zawartości tego związku w tkance tłuszczowej zarówno po jednorazowym podaniu dianizonu, jak i po podaniu mieszaniny dianizonu i selenu.
    Źródło:
    Ecological Chemistry and Engineering. A; 2009, 16, 12; 1617-1626
    1898-6188
    2084-4530
    Pojawia się w:
    Ecological Chemistry and Engineering. A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Identification of model lightening system and design of PID controllers for the purpose of energy savings by using of MATLAB and their functionality in LabVIEW
    Identyfikacja modelu systemu rozjaśniania i zaprojektowania regulatora PID w celu oszczędności energii przy wykorzystaniu programu MATLAB i funkcjonalności LabVIEW
    Autorzy:
    Nagy, L
    Palková, Z
    Valíček, J
    Kiedrowicz, M
    Rokosz, K
    Kovač, P
    Powiązania:
    https://bibliotekanauki.pl/articles/1819293.pdf
    Data publikacji:
    2012
    Wydawca:
    Politechnika Koszalińska. Wydawnictwo Uczelniane
    Tematy:
    sterowanie wzrostu roślin
    regulator PID
    rośliny szklarniowe
    sterowanie oświetleniem
    Opis:
    System sterowany jest częścią pętli i konieczne jest rozważenie go jako osobnej części z konkretnej nieruchomości. Podczas wyboru właściwego regulatora PID ważne jest, aby zrozumieć dynamiczne właściwości kontrolowanego systemu. Na opis tego obiektu zostały opracowane różne metody bilansów energii i następnych modeli matematycznych korygujących przejęcie funkcji transferowych. W praktyce lepiej jest użyć metod, których obserwujemy zachowanie dla konkretnych warunków systemowych (na przykład odpowiedzi na jednostkowy skok na wejściu lub częstotliwość sygnału). Według Behaving wiemy jak matematycznie opisać systemu i następnie wybrać właściwy rodzaj regulatora PID z jego parametrami. Ten artykuł skupia się na identyfikacji systemu oświetlenia dla uprawy roślin szklarniowych oraz prawidłowego zaprojektowania parametrów regulatora PID do sterowania oświetleniem, tak aby zorientowany był on na oszczędności energii.
    Źródło:
    Rocznik Ochrona Środowiska; 2012, Tom 14; 247-261
    1506-218X
    Pojawia się w:
    Rocznik Ochrona Środowiska
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Pliocene to Quaternary stress field change in the western part of the Cen tral West ern Carpathians (Slovakia)
    Autorzy:
    Vojtko, R.
    Hók, J.
    Kováč, M.
    Sliva, L’.
    Joniak, P.
    Šujan, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/2060207.pdf
    Data publikacji:
    2008
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    Western Carpathians
    fault-slip data
    Quaternary stress field
    neotectonics
    palaeostress analysis
    Opis:
    Knowledge of the current tectonic regime plays an essential role in natural hazard assessment, especially in the risk assessment of fault activity. Structural analysis of brittle deformations (using in version techniques) was used to determine the stress field state occurring within Pliocene and Quaternary deposits in the western part of the Central Western Carpathians. The deformation pattern of the reduced stress tensor showed that all structural measurements could be separated into two groups. An older, Late Pliocene fault population was activated un der NNW-SSE oriented extension. A younger, Quaternary fault population reflected origin in a NE–SW extensional tectonic regime and it distinctly showed a change the orientation of the S3 of about 70. The change in tectonic activity, as well as in the stress field orientation, is dated to the Pliocene-Pleis to cene boundary. The Quaternary stress field developed dur ing the post-collisional stage of the orogen. Our study shows that the West ern Carpathian internal units document NE-SW to NNE-SSW extension in the broader region around of the north ern Danube Basin.
    Źródło:
    Geological Quarterly; 2008, 52, 1; 19-19
    1641-7291
    Pojawia się w:
    Geological Quarterly
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Late Miocene fluvial distributary system in the northern Danube Basin (Pannonian Basin System): depositional processes, stratigraphic architecture and controlling factors of the Piešťany Member (Volkovce Formation)
    Autorzy:
    Šujan, M.
    Kováč, M.
    Hók, J.
    Braucher, R.
    Rybár, S.
    Leeuw, A. de
    Powiązania:
    https://bibliotekanauki.pl/articles/2060598.pdf
    Data publikacji:
    2017
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    fluvial distributary system
    facies analysis
    sediment supply
    accommodation
    Pannonian Basin System
    late Miocene
    Opis:
    Aim of the study was to investigate the detailed stratigraphic architecture of the alluvial Volkovce Formation, which was deposited in the northern Danube Basin during the interval between 10 and 6 Ma. Two type locality exposures were subject to facies analysis and interpretation of depositional processes and >500 boreholes served for correlation of spatial variability in the character of the formation. The study was focused on the northern Blatné and western Rišňovce depressions, which are partly separated by the Považský Inovec Mountains horst. It was revealed, that a mostly gravelly fluvial distributary system of the Piešťany Member was deposited in the northern Blatné depression, partly confined by the exposed horst and by incised palaeotopography. The sequence is composed of amalgamated braided river channel bodies with no overbank strata, in response to high sediment supply and low accommodation. The palaeo-stream then crossed the horst in its southern part towards the Rišňovce depression, where there was four times more accommodation. The submerged horst acted as a boundary, where the depositional processes changed to a meandering river and significant overbank deposits started to be preserved. Only small streams were present in the northern Rišňovce depression, which led to very low sediment supply compared to the high accommodation there. The depositional system was affected mainly by the incised palaeotopography, by the location of sediment input together with spatial differences in accommodation rate caused by the activity of the Ripňany Fault on the southeastern side of the Považský Inovec Mts.
    Źródło:
    Geological Quarterly; 2017, 61, 3; 521--548
    1641-7291
    Pojawia się w:
    Geological Quarterly
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Study of Solidification of Continuously Cast Steel Round Billets Using Numerical Modellin
    Autorzy:
    Tkadleckova, M.
    Válek, L.
    Socha, L.
    Saternus, M.
    Pieprzyca, J.
    Merder, T.
    Michalek, K.
    Kováč, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/353911.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    steel
    billet
    continuous casting
    numerical modelling
    metallurgical length
    Opis:
    The paper is dedicated to the verification of solidification of continuously cast round steel billets using numerical modelling based on the finite element method. The aim of numerical modelling is to optimize the production of continuously cast steel billets of round format. The paper describes the pre-processing, processing and post-processing phases of numerical modelling. Also, the problems with determination of the thermodynamic properties of materials and the heat transfer between the individual parts of the casting system, including the definition of the heat losses along the casting strand in the primary and secondary cooling, were discussed. The first results of numerical simulation show the so-called thermal steady state of continuous casting. The temperature field, the metallurgical length and the thickness of the shell at the end of the mould were predicted. The further research will be concentrated on the prediction the risk of the cracks and the porosity based on the different boundary conditions.
    Źródło:
    Archives of Metallurgy and Materials; 2016, 61, 1; 221-226
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-81 z 81

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