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Wyszukujesz frazę "75.47.lx" wg kryterium: Temat


Tytuł:
Ageing phenomena in La-Sr manganites with divalent substituents for manganese
Autorzy:
Merkulov, D.
Badelin, A.
Estemirova, S.
Karpasyuk, V.
Powiązania:
https://bibliotekanauki.pl/articles/1048158.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.-m
75.47.-m
75.47.Lx
81.70.-q
Opis:
Variations of electromagnetic and structural characteristics of La_{1-c+x}Sr_{c-x}Mn_{1-x}Me_{x}O_{3+γ} manganites (Me = Zn, Ni) during storage time up to 36000 hours at room temperature and after frequentative thermal cycling in the 300-573 K range were investigated. Changes of magnetization of all samples were within the error of measurement. In most cases Curie point (T_{C}) showed irregular variations within the range of 20%, while zinc-substituted manganites with relatively high values of "c" exhibited some trend of T_{C} rise. The resistance of all samples increased during storage period. The cell volume of single-phase manganites decreased over time, that may indicates an increase in oxygen content. However, the sample with the highest Ni content (x=0.125) at c=0.19 suffered phase transition "rhombohedral-orthorhombic structures", which cannot be explained by the oxygen absorption. Probably, this effect was due to the rearrangement of the ions and vacancies between crystal sublattices of manganite.
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 529-531
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Automatic Measurement Station for Ferrite Materials Testing
Autorzy:
Charubin, T.
Nowak, P.
Nowicki, M.
Szewczyk, R.
Urbański, M.
Powiązania:
https://bibliotekanauki.pl/articles/1031017.pdf
Data publikacji:
2018-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.60.Ej
75.47.Lx
52.70.Ds
Opis:
The paper presents automatic and modular measurement station for the magnetic materials testing. It allows for measurements of magnetic hysteresis loops under various regimes (sine, triangle or arbitrary magnetizing field, sine or triangle magnetic flux density) and relative permeability curves. The modular nature of the system allows for measurements of magnetic parameters under additional external influences, such as temperature and stress. The system is currently used for measurements of ferrite materials parameters.
Źródło:
Acta Physica Polonica A; 2018, 133, 4; 1049-1052
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the Neglect of Local Coulomb Interaction on Oxygens in Perovskites Described by the Multiband d-p Model
Autorzy:
Rościszewski, K.
Oleś, A.
Powiązania:
https://bibliotekanauki.pl/articles/1029759.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.15.-m
75.25.Dk
75.47.Lx
Opis:
On the example of TiO₄ layer (such as realized in Sr₂TiO₄) we study electronic structure of multiband d-p models describing transition metal perovskites. As suggested by experiment, the studied system is predicted to be a robust nonmagnetic insulator. A realistic treatment of electronic structure requires one to introduce non-zero Coulomb local interactions at 2p oxygen orbitals. However, up till now majority of papers based upon multiband models made an approximation of neglecting such interactions. We show that this simplification does not lead to serious problems in predictions of the electronic structure provided the Coulomb interactions at titanium ions and charge transfer gap are suitably renormalized (so they become entirely different with respect to the true microscopic d-p model parameters).
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 356-358
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis and Properties of Mesoporous Maghemite
Autorzy:
Kotsyubynsky, V.
Hrubiak, A.
Moklyak, V.
Mohnatska, L.
Fedorchenko, S.
Powiązania:
https://bibliotekanauki.pl/articles/1030886.pdf
Data publikacji:
2018-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.47.Lx
75.75.Cd
61.46.-w
81.16.Be
Opis:
Mesoporous maghemite (γ -Fe₂O₃), obtained by thermal decomposition of iron citrate xerogel hydrate, was investigated by X-ray diffraction, scanning electron microscopy, the Mössbauer and impedance spectroscopies and low temperature nitrogen adsorption. The influence of precursor molar concentration on the material morphology, crystalline and magnetic microstructures and electric conductivity was studied. Obtained results open up the possibility for synthesis of ultrafine γ -Fe₂O₃ with controlled structural and morphological characteristics.
Źródło:
Acta Physica Polonica A; 2018, 133, 4; 1035-1037
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Temperature Influence on the Functional Properties of Inductive Components with Mn-Zn Ferrite Cores
Autorzy:
Jackiewicz, D.
Kachniarz, M.
Bieńkowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/1030884.pdf
Data publikacji:
2018-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
84.30.Jc
75.47.Lx
75.50.Gg
Opis:
The paper presents the results of investigation of the temperature influence on the inductance and power losses in ferrite cores. Such effect can significantly influence the utility parameters of electronic devices, particularly in precision equipment. For example slight parameter change in this type of components in measuring devices can cause significant changes in output parameters. It is also equally important for mobile devices where increase of losses can limit the duration of service. Special measurement system composed of hysteresis graph, cryostat and PC was utilized to perform the experiment. The cores used during the investigation had closed magnetic circuit. In order to perform measurements of magnetic properties of the material, two sets of windings (magnetizing and sensing) were made on each core. The cores were placed in a cryostat, which was used to set the temperature value within the range from -20 to +50°C. The magnetic properties were measured by the hysteresis graph, to assess the influence of the temperature on the functional parameters.
Źródło:
Acta Physica Polonica A; 2018, 133, 4; 1038-1040
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Characterization of epitaxial LSMO films grown on STO substrates
Autorzy:
Španková, M.
Štrbík, V.
Chromik, Š.
Zheng, D.
Li, J.
Machajdík, D.
Kobzev, A.
Plecenik, T.
Sojková, M.
Powiązania:
https://bibliotekanauki.pl/articles/1054697.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.37.Ps
75.47.Lx
75.70.Ak
81.15.Fg
Opis:
Epitaxial manganite La_{0.67}Sr_{0.33}MnO₃ (LSMO) layers, with a thickness of 20-50 nm, are prepared on single crystal (001) SrTiO₃ (STO) substrates by pulsed laser deposition technique. Structural characterization (composition analysis, surface morphology), investigated by the Rutherford backscattering spectroscopy and atomic force microscopy, reveals the growth of stoichiometric LSMO films with a smooth surface (root-mean-square value of 0.21-1.6 nm). The prepared LSMO films possess high Curie temperature ( ≈ 412 K), low room temperature resistivity (1-2 mΩ cm) and maximum of temperature coefficient of resistivity TCR = 2.7% K¯¹ at 321 K.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 848-850
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of the Jahn-Teller Distortion on Double Exchange Interaction in $La_{0.8}K_{0.2}MnO_3$ Nanoparticles
Autorzy:
Mihalik, M.
Zentková, M.
Vavra, M.
Mihalik Jr., M.
Lazúrová, J.
Girman, V.
Konieczny, P.
Fitta, M.
Il'kovič, S.
Powiązania:
https://bibliotekanauki.pl/articles/1398285.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.-y
75.47.Lx
75.30.-m
75.30.Kz
Opis:
Electric resistance and effect of hydrostatic pressure on magnetic properties has been studied on the $La_{0.8}K_{0.2}MnO_3$ nanoparticles. Magnetic phase transition is affected by pressure only slightly, the Curie temperature $T_{C}$ decreases with the rate of -1.02 K/GPa, on samples with orthorhombic structure where the Jahn-Teller distortion of lattice is large. On the other hand, $T_{C}$ increases with the rate of 20.1 K/GPa on samples with rhombohedral structure, where the Jahn-Teller distortion of lattice is absent. Insulator type of electrical resistance is characteristic feature of sample with large Jahn-Teller distortion of lattice and insulator-metal transition was observed on samples where the Jahn-Teller distortion is negligible. Our results are in line with theoretical calculation predicting that double exchange interaction is suppressed by the Jahn-Teller distortion.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 875-877
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of Doping on the Structural Distortion of $La_{0.7}Dy_{0.3}Mn_{1-x}Zn_xO_3$
Autorzy:
López, J.
Ríos, M.
Mendoza, G.
Powiązania:
https://bibliotekanauki.pl/articles/1398317.pdf
Data publikacji:
2017-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.47.Lx
61.50.-f
Opis:
Structural properties were studied in the orthorhombic perovskite $La_{0.7}Dy_{0.3}Mn_{1-x}Zn_{x}O_3$, synthesized in the range 0 ≤ x ≤ 0.4. X-ray diffraction data, refined by the Rietveld analysis, shows for x < 0.1 the presence of stretched octahedra on the Mn-O plane, and, for x > 0.1, the existence of elongated octahedra along the c axis. Increased Zn doping causes a direct structural effect: one Zn atom distorts four neighboring MnO₆ octahedra on the Mn-O plane. It was observed that the unit cell volume containing Dy decreases as x increases, whereas the unit cell volume containing La increases as x decreases.
Źródło:
Acta Physica Polonica A; 2017, 131, 5; 1254-1255
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Exchange bias effect in NdFeO₃ system of nanoparticles
Autorzy:
Vavra, M.
Zentková, M.
Mihalik, M.
Mihalik Jr., M.
Lazúrová, J.
Girman, V.
Perovic, M.
Kusigerski, V.
Roupcova, P.
Jaglicic, Z.
Powiązania:
https://bibliotekanauki.pl/articles/1054801.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.47.Lx
75.50.Tt
75.70.Rf
75.60.Jk
Opis:
We study the effect of nanometric size on the crystal structure, magnetic environment of iron and magnetization in NdFeO₃ system of nanoparticles. The average particle size of NdFeO₃ nanoparticles increases with annealing at 600°C from about 15 nm to 40 nm. The smallest particles on annealed sample have size approximately 30 nm and typically have character of single crystalline samples. All samples adopt orthorhombic crystal structure, space group Pnma with lattice parameters a =5.5817 Å, b=7.7663 Å and c =5.456 Å for as prepared sample. The presence of superparamagnetic particles was indicated by the Mössbauer measurements. The reduction of dimensionality induces a decrease of T_{N1} from 691 K to 544 K. The shift of magnetic hysteresis loop in vertical and horizontal direction was observed at low temperatures after cooling in magnetic field. We attribute such behaviour to exchange bias effect and discuss in the frame of core-shell model.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 869-871
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:
Phase Structure and Heat Generation in the Co-Precipitated Magnetite Nanoparticles
Autorzy:
Pawlik, P.
Pruba, M.
Pawlik, K.
Kotynia, K.
Powiązania:
https://bibliotekanauki.pl/articles/1030238.pdf
Data publikacji:
2017-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.47.Lx
78.67.Bf
78.70.Ck
76.80.+y
87.50.S-
Opis:
In the present studies the phase structure and magnetic ordering of magnetite nanoparticles were investigated. The powder samples were obtained by co-precipitation from Fe(III) and Fe(II) salts. SiO₂ coating was performed using the modified Stöber process. X-ray diffraction studies revealed presence of the only one Fe₃O₄ crystalline phase both for the non-coated and SiO₂-coated samples. The Mössbauer studies have shown differences in shapes of measured spectral lines for Fe₃O₄ particles subjected to the Stöber process and non-coated particles. The heating efficiency was measured for glycerol dispersed nanoparticles. The analysis have shown changes in specific loss power depending on the concentration of the nanoparticles and amplitude of alternating magnetic field.
Źródło:
Acta Physica Polonica A; 2017, 131, 5; 1217-1221
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:
Preparation and Magnetic Characteristics of $Co_{1-δ}Zn_{δ}Fe_2O_4$ Ferrite Nanopowders
Autorzy:
Kubisztal, M.
Herok, I.
Karolus, M.
Prusik, K.
Haneczok, G.
Powiązania:
https://bibliotekanauki.pl/articles/1398315.pdf
Data publikacji:
2017-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.47.Lx
75.50.Gg
75.50.Tt
75.75.-c
75.75.Cd
Opis:
In the present paper the $Co_{1-δ}Zn_{δ}Fe_2O_4$ (0 ≤ δ ≤ 1) ferrite nanopowders with a spinel type structure were synthesized using a chemical co-precipitation technique with constant flow rate $ν _{FR}$=120 cm³/min at three different reaction temperatures i.e. $T_r$ =50°C, 70°C and 90°C. Magnetic and structural characteristics of the obtained materials were investigated by means of X-ray diffraction method, transmission electron microscopy and vibrating sample magnetometer. In the course of studies hysteresis loops M(μ₀H) and the relations of magnetization $M_{7T}$ (determined at $\text{}_{μ0}H $=7 T), squareness ratio S and the Néel temperature $T_{N}$ versus Zn content were determined and discussed in detail. It was shown that for δ<0.6 the increase in reaction temperature $T_r$ results in a significant increase of the measured magnetic characteristics. In particular, in the case of $Co_{0.8}Zn_{0.2}Fe_2O_4$ ferrite nanopowder magnetization $M_{7T}$ reaches maximal value of about 80 emu/g.
Źródło:
Acta Physica Polonica A; 2017, 131, 5; 1236-1239
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Size dependent heating efficiency of multicore iron oxide particles in low-power alternating magnetic fields
Autorzy:
Smolkova, I.
Kazantseva, N.
Vitkova, L.
Babayan, V.
Vilcakova, J.
Smolka, P.
Powiązania:
https://bibliotekanauki.pl/articles/1054706.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.47.Lx
75.50.Mm
75.60.Jk
75.75.-c
75.78.-n
Opis:
Aggregates of superparamagnetic nanoparticles, so called multicore particles get much attention due to collective magnetic behaviour. Despite the fact that saturation magnetization and coercivity of multicore particles are lower than for single particles of comparable size, they can generate large amount of heat in alternating magnetic field. This makes them promising for magnetic hyperthermia. However, correlation between internal magnetic structure of multicore particles and their heating ability in alternating magnetic fields are not clear yet. Detailed experimental investigations are required to determine the optimal sizes of multicore particles and the alternating magnetic field parameters to obtain maximal heat. In this study, we demonstrated how hydrodynamic size of multicore particles influences alternating magnetic field energy absorption. Dense aggregates composed of bare magnetic iron oxide nanoparticles of 13 nm were obtained by coprecipitation. Further peptization allowed to gain aqueous dispersions of multicore particles with various hydrodynamic size, varing from 85 to 170 nm, due to electrostatic stabilization. Multicore particles dispersions have saturation magnetization of 40 A m²/kg_{Fe₃O₄} and coercivity of 79.6 A/m regardless of their size. Dispersion of 85 nm multicore particles is stable and provides specific loss power of 42 W/g_{Fe}. Further increase of hydrodynamic size leads to low stability and loss of the ability to generate heat in alternating magnetic field.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 663-665
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Elastic Properties of Colossal Magnetoresistive Manganites $R_{0.67} Sr_{0.33} Mn O_3$ (R = Pr, Nd, Gd)
Autorzy:
Reddy, Y.
Powiązania:
https://bibliotekanauki.pl/articles/1398673.pdf
Data publikacji:
2016-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.47.Gk
75.47.Lx
62.20.de
43.20.Hq
Opis:
The polycrystalline bulk samples of $R_{0.67} Sr_{0.33} Mn O_3$ (R = Pr, Nd, Gd) were prepared by solid state reaction method and characterized by powder X-ray diffraction. The room temperature elastic behavior of these materials was investigated by employing ultrasonic pulse transmission technique at 1 MHz. The values of elastic constants were computed from longitudinal and shear velocities. The measured values were corrected to zero porosity using Hasselman and Fulrath's formulae. The variation of elastic moduli with the size of rare earth ion is interpreted in terms of strength of interatomic bonding.
Źródło:
Acta Physica Polonica A; 2016, 129, 1; 113-116
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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