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Wyświetlanie 1-11 z 11
Tytuł:
$Fe_2O_3/SiO_2$ Hybrid Nanocomposites Studied Mainly by Mössbauer Spectroscopy
Autorzy:
Lančok, A.
Bezdička, P.
Klementová, M.
Závěta, K.
Savii, C.
Powiązania:
https://bibliotekanauki.pl/articles/1813926.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Tt
76.80.+y
Opis:
Magnetic nanocomposites exhibit promising applications in many areas, for example optics, electronics, biology, medicine, etc. The main goal of this study was to synthesize magnetic ε-$Fe_2O_3$ nanoparticles embedded in amorphous $SiO_2$. These materials were prepared by the help of ultrasonic activation and subsequent annealing in nitrogen atmosphere or air with concentrations of iron oxide of about 20 and 30 wt.%. The structure and properties of the final product were analysed by the Mössbauer spectrometry as well as by X-ray diffraction, scanning electron microscopy, and high resolution transmission electron microscopy. They strongly depend on the initial conditions of preparation.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 577-581
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Phase Structure and Magnetic Properties of Fe-Nb-B-Pt Type of Bulk Nanocrystalline Alloys
Autorzy:
Ziółkowski, G.
Chrobak, A.
Randrianantoandro, N.
Klimontko, J.
Powiązania:
https://bibliotekanauki.pl/articles/1367778.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.Bc
75.50.Tt
75.60.76.80.+y
Opis:
The paper refers to magnetic and structure properties of the $(Fe_{80}Nb_{6}B_{14})_{1-x}Pt_{x}$ (x=0.15, 0.3, 0.4 and 0.6) bulk nanocrystalline alloys prepared using the vacuum suction casting technique. The samples were in the form of rods with diameters ranging from 0.5 mm to 1.5 mm. It was shown that the optimal Pt content is x=0.4 with the coercive field equal to 0.2 T and maximum energy product $|BH|_{max}=11.2 kJ//m^{3}$. The magnetic properties can be associated with Fe-Pt, Fe and Fe-B phases, depending on the alloy composition.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 174-175
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:
Mössbauer Spectrometry in FeMoCuB-Type Nanocrystalline Alloys
Autorzy:
Miglierini, M.
Powiązania:
https://bibliotekanauki.pl/articles/1813519.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Tt
61.46.+w
61.66.-f
76.80.+y
Opis:
The applicability of the Mössbauer spectrometry to the study of $Fe_{91-x}Mo_8Cu_1B_x$ (x = 12, 15, 17) nanocrystalline alloys prepared by controlled annealing of ribbon-shaped amorphous precursors is demonstrated. Differences between both surfaces of the ribbons are pointed out to be due to preparation conditions. Conclusions from the Mössbauer spectrometry are supported by diffraction of synchrotron radiation, X-ray diffraction, and atomic field microscopy investigations.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 47-50
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
Tytuł:
Magnetic Hyperfine Fields of Nanoperm Alloys
Autorzy:
Miglierini, M.
Kohout, J.
Lančok, A.
Šafářová, K.
Powiązania:
https://bibliotekanauki.pl/articles/1428957.pdf
Data publikacji:
2012-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Tt
75.75.-c
76.80.+y
76.60.-k
68.37.Rt
Opis:
Magnetic hyperfine fields of $Fe_{90}Zr_7B_3$ Nanoperm nanocrystalline alloy are characterized by $\text{}^{57}Fe$ Mössbauer spectrometry and $P^{57}Fe$ NMR as well as by magnetic force microscopy. $\text{}^{57}Fe$ NMR enables to distinguish a broad signal of iron atoms located in a residual amorphous matrix from a narrow one which belongs to Fe in nanograins. The former coincides with the distribution of hyperfine fields obtained from $\text{}^{57}Fe$ Mössbauer spectroscopy. In addition, it is possible to make a distinction between NMR signals of the Fe nanograins located in magnetic domains from that of the nanograins positioned in domain walls. This is confirmed by magnetic force microscopy where appearance of maze-domains is observed.
Źródło:
Acta Physica Polonica A; 2012, 121, 5-6; 1263-1265
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic and Mössbauer Study of Cerium-Based Reactive Sorbent
Autorzy:
Jiraskova, Y.
Bursik, J.
Zivotsky, O.
Lunacek, J.
Janos, P.
Powiązania:
https://bibliotekanauki.pl/articles/1032876.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Tt
75.60.Ej
76.80.+y
61.46.Df
75.30.Kz
75.50.Bb
Opis:
A new kind of magnetically separable composite consisting initially of magnetite and cerium carbonate nanograins was investigated using magnetic and Mössbauer methods at room and low temperatures. Various stages of calcination treatment in air resulted in a transformation of the cerium carbonate into cerium dioxide and magnetite into more complicated iron oxide compositions. The final CeO₂ nanograins on the surface of α-Fe₂O₃ were obtained after calcination at 973 K.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1096-1098
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-11 z 11

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