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Wyświetlanie 1-9 z 9
Tytuł:
Magnetic hardening induced in RCo₅ (R = Y, Gd, Sm) by short HEBM
Autorzy:
Łopadczak, P.
Bajorek, A.
Prusik, K.
Zubko, M.
Chełkowska, G.
Powiązania:
https://bibliotekanauki.pl/articles/1048324.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.-b
81.07.Bc
75.50.Ww
75.60.-d
75.75.Cd
Opis:
The paper is focused on the magnetic and structural properties of RCo₅ (R = Y, Gd, Sm) intermetallics fabricated by high energy ball - milling (HEBM). The investigated samples were first produced by arc-melting as bulk materials and then were milled for 1h in dimethylformamide with balls to powder ratio 10:1. The influence of the HEBM parameters on the microstructure was investigated by a variety of complementary measurement methods. The Rietveld refinement was performed to estimate the dependence of crystallite size and microstrain on type of sample. The hysteresis loops were recorded by SQUID magnetometer at 2 K and 300 K and at magnetic field up to μ₀H=7 T. The impact of short HEBM process is visible as the enhancement of coercivity and simultaneous reduction of the saturation magnetization.
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 688-690
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural Characterization of $La_{1-x}Sr_xCoO_3$ Thin Films Deposited by Pulsed Electron Deposition Method
Autorzy:
Cieniek, Ł.
Kopia, A.
Cyza, A.
Kowalski, K.
Kusiński, J.
Powiązania:
https://bibliotekanauki.pl/articles/1398370.pdf
Data publikacji:
2016-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.15.-z
81.10.Bk
81.07.Bc
68.55.-a
68.55.J-
68.55.Nq
68.37.-d
Opis:
The aim of the presented research was to investigate the influence of strontium dopant on the structure and composition of $La_{1-x}Sr_{x}CoO_3$ (x=0, 0.1, 0.2) perovskite thin films. Pure and Sr doped LaCoO₃ thin films were grown by pulsed electron deposition technique on crystalline epi-polished Si/MgO substrates. Numerous analytical techniques (scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction) were applied to characterize their phase/chemical composition, structure and surface morphology. X-ray diffraction analysis showed the presence of pure LaCoO₃ perovskite phase in the undoped thin film. For Sr doped thin films $La_{0.8}Sr_{0.2}CoO_3$ (x=0.2), $La_{0.9}Sr_{0.1}CoO_3$ (x=0.1) small contents of La₂ O₃ and LaSrCoO₄ phases were noticed. The crystallite sizes, calculated from the Williamson-Hall plots, were about 18 nm for all analyzed films. According to scanning electron microscopy/atomic force microscopy observations, obtained thin films were free from defects and cracks. Atomic force microscopy (tapping mode) analysis revealed the differences in the shape and quantity of surface crystallites for all thin films as a result of Sr doping and different deposition parameters. Atomic force microscopy technique also allowed measurement of roughness parameters for analyzed samples. X-ray photoelectron spectroscopy analyses of chemical states of elements of thin films showed that their chemical state was stable across the film thickness and even at the interface with the MgO substrate. X-ray photoelectron spectroscopy analysis also allowed to evaluate chemical states and atomic concentration of La, Co, and Sr elements within cross-sections of deposited thin films.
Źródło:
Acta Physica Polonica A; 2016, 130, 4; 1121-1123
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Phase Stability of $(Fe_{80}Nb_{6}B_{14})_{0.9}Tb_{0.1}$ Bulk Nanocrystalline Magnet
Autorzy:
Chrobak, A.
Ziółkowski, G.
Randrianantoandro, N.
Powiązania:
https://bibliotekanauki.pl/articles/1367802.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.Bc
75.50.Tt
75.60.d
76.80.+y
Opis:
The paper refers to phase stability of the $(Fe_{80}Nb_{6}B_{14})_{0.9}Tb_{0.1}$ bulk nanocrystalline alloys prepared using the vacuum suction casting technique. The samples were in the form of rods with diameters d=2, 1.5, 1 and 0.5 mm. Heating up to 900 K reveals structural changes that occur at temperatures above 680 K (DSC and M(T) measurements). The phase analysis, using Mössbauer spectra, indicates the decrease of $Tb_{2}Fe_{14}B$ and increase of Fe content in the samples after the heat treatment. The most stable is the alloy with d=1 mm, where the formation of α-Fe phase was not observed. The decrease of d causes significant hardening i.e. coercive field increases from 0.57 T to 2.66 T for d=2 mm and d=0.5 mm, respectively.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 176-177
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Cooling Rate on Magnetic Properties of $(Fe_{80}Nb_{6}B_{14})_{1-x}Tb_{x}$ Type of Bulk Nanocrystalline Alloys
Autorzy:
Chrobak, A.
Ziółkowski, G.
Haneczok, G.
Powiązania:
https://bibliotekanauki.pl/articles/1367856.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.Bc
75.50.Tt
75.60.d
76.80.+y
Opis:
The paper refers to magnetic properties of the $(Fe_{80}Nb_{6}B_{14})_{1-x}Tb_{x}$ (x=0.06 and x=0.08) bulk nanocrystalline alloys prepared using the vacuum suction casting technique. The samples were in the form of rods with diameters of d=1.5 mm, 1 mm and 0.5 mm. It was shown that for the alloys with x=0.08 the significant magnetic hardening with the decrease of sample diameter was observed. For d=0.5 mm the coercive field equals 2.46 T and the maximum energy product $|JH|_{max}$=77.2 kJ/$m^{3}$.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 178-179
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetization Processes of Nanoparticles Embedded into Ferromagnetic Matrix
Autorzy:
Ziółkowski, G.
Chrobak, A.
Powiązania:
https://bibliotekanauki.pl/articles/1387548.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.Bc
75.50.Tt
75.60.-d
75.78.Cd
Opis:
The paper refers to computer simulations of interactions between magnetically hard particle embedded into ultra-hard matrix. We used simulated annealing and Monte Carlo simulations in a frame of the 3D Heisenberg model. The performed simulations reveal that the particles show additional exchange anisotropy dependent on "frozen" spin direction in the matrix and the angle between matrix and particle easy magnetization axes. The particle-matrix coupling are responsible for multi-phase magnetic hysteresis shape and exchange-bias like effect.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 597-599
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Size Effect of Hard Magnetic Properties of Fe-Nb-B-Tb Milled Alloys
Autorzy:
Granek, K.
Ziółkowski, G.
Chrobak, A.
Klimontko, J.
Talik, E.
Powiązania:
https://bibliotekanauki.pl/articles/1030390.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.Bc
75.50.Tt
75.60.d
76.80.+y
Opis:
The paper refers to magnetic and structural properties of powders made of Fe-Nb-B-Tb ultra-high coercive alloy. The initial alloy was milled in a low energy mill for 1 h and 14 h. With increasing milling time we observed gradual deterioration of hard magnetic properties i.e. the coercive field decreases from 5.51 T to 0.14 T for the bulk alloy and 14 h milled powder, respectively. However, for the 1 h milling time the micrometric powder reveals quite high coercivity of 2.77 T which is promising for possible applications in magnetic composites.
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 645-647
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nanoscale Analysis of Superparamagnetic Systems
Autorzy:
Chrobak, A.
Ziółkowski, G.
Powiązania:
https://bibliotekanauki.pl/articles/1033082.pdf
Data publikacji:
2017-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.Bc
75.50.Tt
75.60.-d
76.80.+y
Opis:
The paper refers to a kind of nanoscale characterization of superparamagnetic materials above and below the so-called blocking temperature. It is propose to apply the Stoner-Wohlfarth model of nanoparticles magnetization supplemented by the two-level kinetic model, determining behavior in T>0. This approach allows determination of distribution of magnetic moments and energetic barriers of magnetic objects based on magnetization curves. In many cases, the determined distribution of magnetic moments can be recalculated into average size of the magnetic objects giving finally a nano/microscaled picture of the material. The proposed method was successfully used in characterization of diluted magnetics, nanocomposites, powders and even for human hemoglobin. In the paper the basic theory and its application to the nanoscale characterization is discussed in detail.
Źródło:
Acta Physica Polonica A; 2017, 131, 5; 1371-1374
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimization of soft magnetic properties in Fe₈₂Nb₂B₁₄RE₂ (RE = Y, Gd, Tb and Dy) group of amorphous alloys
Autorzy:
Chrobak, A.
Haneczok, G.
Zivotsky, O.
Hendrych, A.
Kansy, J.
Kotur, B.
Powiązania:
https://bibliotekanauki.pl/articles/1113556.pdf
Data publikacji:
2016-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.Bc
75.50.Tt
75.60.-d
76.80.+y
Opis:
Enhancement of soft magnetic properties in the selected group of amorphous alloys was examined by different experimental methods. It was shown that permeability for annealed samples (at T_{a} for 1 h; 300 K < T_{a} < 900 K) plotted vs. T_{a} shows a maximum at which is 700, 725, 725, and 750 K for Fe₈₂Nb₂B₁₄Y₂, Fe₈₂Nb₂B₁₄Gd₂, Fe₈₂Nb₂B₁₄Tb₂ and Fe₈₂Nb₂B₁₄Dy₂ alloy, respectively. For samples after the optimization annealing permeability is at least 10 times higher than in the as-quenched state. The optimized microstructure is free of iron nanograins and corresponds to so-called relaxed amorphous phase.
Źródło:
Acta Physica Polonica A; 2016, 130, 4; 916-919
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Transition and Rare Earth Elements on Magnetic Properties of Fe-Nb-B-M (M~=~Ni, Ag, Gd,~Tb) Bulk Nanocrystalline Alloys
Autorzy:
Ziółkowski, G.
Randrianantoandro, N.
Chrobak, A.
Klimontko, J.
Kądziołka-Gaweł, M.
Haneczok, G.
Powiązania:
https://bibliotekanauki.pl/articles/1428970.pdf
Data publikacji:
2012-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.Bc
75.50.Tt
75.60.-d
76.80.+y
Opis:
In this work we present magnetic properties of the $(Fe_{80}Nb_6B_{14})_{1-x}M_x$ (where M = Ni, Ag, Gd, Tb and x = 0.08, 0.16, 0.32) bulk nanocrystalline alloys prepared by making use of mould casting technique. The applied preparation technique is favorable to nanocrystallization of the alloys with mean diameters of crystallites ranged from about 10 nm to 30 nm. Phase identification reveals a formation of ternary $RE_2Fe_{14}B$ and binary $REFe_2$ phases dependently on the alloy composition. It was found that for the alloys with Ag addition magnetic moment of Fe atom increases from 2.26 $μ_{B}$ to 3.36 $μ_{B}$ for x = 0.08 and x = 0.32, respectively. For Ni addition this quantity decreases with increasing x due to appearing of Fe-Ni (fcc) phases. For Gd, Tb additions the alloys are ferrimagnetic with compensation composition ranged between x = 0.08 and x = 0.16. The both rare earth alloying additions cause a significant magnetic hardening especially in the case of Tb.
Źródło:
Acta Physica Polonica A; 2012, 121, 5-6; 1266-1269
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-9 z 9

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