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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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
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

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