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1
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Influence of Al and Ga on Formation of the La(Fe,Si)_{13}-Type Phase in the LaFe_{11.14}Co_{0.66}Si_{1.2-x}M_x (where x=0.1, 0.2, 0.3; M=Al, Ga) Alloys

100%
Gębara P.
Acta Physica Polonica A
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2016
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vol. 129
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issue 2
193-196
EN
In the present work the influence of Al and Ga on formation of La(Fe,Si)_{13}-type phase in magnetocaloric LaFe_{11.14}Co_{0.66}Si_{1.2-x}M_x (where x=0.1, 0.2, 0.3; M = Al, Ga) alloys subjected to annealing at 1323 K for 15 days was studied using the Mössbauer spectroscopy. For annealed samples, two crystalline phases were recognized: the dominant paramagnetic La(Fe,Si)_{13}-type phase, and minor fraction of ferromagnetic α -Fe(Co,Si). It was revealed that Al improved formation of 1:13 phase in contrast to Ga, which caused reduction of the ability of formation of the expected phase.
2
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Investigations of the Magnetic Phase Transition in the LaFe_{11.14}Co_{0.66}Si_{1.1}M_{0.1} (Where M = Al or Ga) Alloys

100%
Gębara P.
Acta Physica Polonica A
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2017
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vol. 131
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issue 4
798-800
EN
The aim of the present work was to study the phase transition in the LaFe_{11.14}Co_{0.66}Si_{1.1}M_{0.1} (where M = Al or Ga) alloys. Research was carried out using field dependences of magnetization measured at a wide temperature range. Positive slope of the Arrott plots showed that magnetic phase transition in both investigated samples was of second order nature. The temperature dependences of the Landau coefficients also revealed second order phase transition in both specimens. The analysis carried out using universal curve confirmed second nature of phase transition in both samples.
3
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Influence of Partial Substitution of Fe by Mn on the Thermomagnetic Properties of Magnetocaloric LaFe_{11.2}Co_{0.7}Si_{1.1} Alloy

64%
Gębara P., Marcin J.
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EN
The aim of this paper was to study the influence of partial substitution of Fe by Mn in the LaFe_{11.2-x}Mn_{x}Co_{0.7}Si_{1.1} (where x=0.1, 0.2 and 0.3) alloys. Measurements revealed that a systematic increase of Mn in the alloy composition resulted in a decrease of the Curie temperature, which correlated with a decrease of the lattice parameter of the La(Fe,Si)₁₃- type phase. For samples corresponding to Mn content x=0.1 and 0.2 a decrease of magnetic entropy change was observed. However in the case of the sample with x=0.3 an increase of magnetic entropy change was detected.
4
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Investigation of Critical Behavior in Gd₇₅Ge₁₅Si₅Ce₅ Alloy

64%
Gębara P., Hasiak M.
Acta Physica Polonica A
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2017
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vol. 131
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issue 5
1232-1235
EN
The main goal of the present work was to study the critical behavior in the as-quenched Gd₇₅Ge₁₅Si₅Ce₅ (wt%) in the vicinity of the critical temperature T_{C}. The second order phase transition from a ferro- to a paramagnetic state was confirmed by the positive slope of the Arrott plots and analysis of temperature evolution of the Landau coefficients. The critical exponents have been revealed using the Kouvel-Fisher method and yield β=0.376±0.006, γ=1.032±0.006 and δ=3.835±0.008. The Curie temperature for the as-quenched Gd₇₅Ge₁₅Si₅Ce₅ equals 275.7±0.1 K.
5
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Magnetocaloric Effect in Amorphous and Partially Crystallized Fe₈₀Zr₇Cr₆Nb₂Cu₁B₄ Alloy

52%
Łukiewska A., Olszewski J., Hasiak M., Gębara P.
Acta Physica Polonica A
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2018
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vol. 133
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issue 3
676-679
EN
In the present work the microstructure and thermomagnetic properties of Fe₈₀Zr₇Cr₆Nb₂Cu₁B₄ ribbon in the as-quenched state and after the accumulative annealing in the temperature range 600-800 K for 10 min were studied using Mössbauer spectroscopy and vibrating sample magnetometry. The second order phase transition from ferro- to paramagnetic state is observed. The Curie temperature T_{C} defined as inflection point on the magnetization versus temperature curve recorded on zero-field cooled mode equals 262.5 K for the as-quenched material. With increasing the annealing temperature increase of T_{C} is observed. The maximum value of the magnetic entropy change (-ΔS) observed in the vicinity of the Curie point is equal to 0.85 J/(kg K) for the alloy in the as-quenched state. Moreover, for the samples annealed up to 750 K for 10 min the low intensity maximum at about 190 K related to the supplementary magnetic phase is observed. The presence of this phase was confirmed as additional component visible on hyperfine field distributions of Mössbauer spectra.
6
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Magnetic Properties of the Nanocrystalline Nd9.6Fe64.32Nb4B22.08 Alloy Ribbons

52%
Szwaja M., Pawlik P., Wysłocki J., Gębara P.
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issue 1
7
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Structural and Magnetic Studies of the LaFe_{11.2}Co_{0.7-x}Mn_xSi_{1.1} (where x=0.1, 0.2) Alloys

52%
Gębara P., Marcin J., Glińska A., Wysłocki J.
Acta Physica Polonica A
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2018
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vol. 133
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issue 2
232-235
EN
The aim of present work was to study the influence of partial substitution of Co by Mn in the LaFe_{11.2}Co_{0.7}Si_{1.1} alloy on its structure and magnetic properties. The X-ray diffraction studies revealed coexistence of dominant pseudobinary fcc La(Fe,Si)_{13}-type phase with minor fraction of α-Fe. Moreover, the increase of Mn content causes decrease of the lattice parameter and the Curie temperature. The values of magnetic entropy change obtained for both investigated alloys are almost identical and close to 12 J/(kg K) under the change of external magnetic field ≈5 T. Investigations of magnetic phase transition confirmed its second order nature in the case of both specimens.
8
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Structure and Magnetic Properties of Fe-B-Si-Zr Metallic Glasses

52%
Babilas R., Radoń A., Gębara P.
Acta Physica Polonica A
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2017
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vol. 131
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issue 4
726-728
EN
Fe-based amorphous alloys were characterized by X-ray diffraction, transmission Mössbauer spectroscopy and vibrating sample magnetometry. The studies were performed on (Fe_{0.75}B_{0.15}Si_{0.1})_{100-x}Zr_{x} (x=0, 1, 3) metallic glasses in the form of ribbons. The glassy samples were prepared by the "melt spinning" technique in argon protective atmosphere. The XRD patterns show the broad diffraction halo that is typical for amorphous Fe-based alloys. The Mössbauer spectroscopy allows to study the local environments of the Fe atoms in the glassy state, showing the changes in the amorphous structure due to the changing of Zr addition. From hysteresis loops obtained from vibrating sample magnetometry measurements, coercive force and saturation magnetization were determined versus different Zr content. The obtained magnetic properties allow to classify the studied amorphous alloys in as-cast state as soft magnetic materials.
9
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Effect of Preparing Conditions on the Phase Constitution and Magnetic Properties of Nd-Pr-Fe-Zr-B Alloy Ribbons

52%
Ceglarek A., Gębara P., Płusa D.
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EN
The aim of presented work was to study influence of preparing conditions on phase constitution and magnetic properties of the RE-Fe-B nanocomposite magnets doped with Zr. X-ray studies carried out for samples obtained under lower pressure of Ar atmosphere (0.6×10⁵ Pa) revealed higher ability to formation of nanocrystalline structure. In case of higher pressure of Ar (0.8×10⁵ Pa) it was possible to obtain full amorphous ribbon during melt-spinning process. The best magnetic properties (means the higher values of coercivity field _{J}H_{c}, remanence J_{r} and maximum energy product (BH)_{max}) were measured for sample prepared with the lowest copper wheel speed 20 m/s and higher pressure of Ar (0.8×10⁵ Pa).
10
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Measurements of Magnetocaloric Effect in LaFe_{11.14}Co_{0.66}Si_{1.2-x}Al_{x} (x=0.1, 0.2, 0.3) Alloys

52%
Gębara P., Pawlik P., Michalski B., Wysłocki J.
Acta Physica Polonica A
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2015
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vol. 127
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issue 2
576-578
EN
In the present work, phase constitution and thermomagnetic properties of LaFe_{11.14}Co_{0.66}Si_{1.2-x}Al_{x} (where x = 0.1, 0.2, 0.3) alloys were investigated. Ingot samples were obtained by arc-melting under the low pressure of Ar atmosphere. Subsequently samples were annealed at 1323 K for 15 days. X-ray diffraction of all samples revealed coexistence of two crystalline phases dominant La(Fe,Si)_{13}-type and minor bcc α -Fe. Furthermore, the magnetic measurements at various temperatures allowed to study the Curie temperature, magnetic entropy changes and relative cooling power.
11
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Influence of Nb Addition on Magnetic Properties of the Nanocrystalline (Nd₁₀Fe₆₇B₂₃)_{100-x}Nbₓ (where x = 1, 2, 4) Alloy Ribbons

46%
Szwaja M., Pawlik K., Pawlik P., Gębara P., Michalski B.
Acta Physica Polonica A
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2015
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vol. 127
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issue 2
623-625
EN
In the present work the magnetic properties and phase constitution of (Nd₁₀Fe₆₇B₂₃)_{100-x}Nbₓ (where x = 1, 2, 4) alloys in the form of ribbons were investigated. The base alloys were prepared by arc-melting the high purity elements with pre-alloyed Fe-B under an Ar atmosphere. The ribbon samples were obtained by controlled atmosphere melt-spinning technique. In order to generate the nanocrystalline microstructure and hard magnetic properties, samples were annealed at various temperatures (from 923 K to 1023 K) for 5 min. The aim of the present work was to determine the influence of Nb admixture and annealing conditions on the phase constitution and magnetic properties.
12
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Effect of Ga Addition on Structure and Magnetic Properties of the LaFe_{11.14}Co_{0.66}Si_{1.2-x}Ga_{x} (x=0.1, 0.2, 0.3) Alloys

46%
Gębara P., Pawlik P., Michalski B., Wysłocki J., Kotynia K.
Acta Physica Polonica A
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2015
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vol. 128
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issue 1
87-90
EN
In the present work, the phase constitution and magnetic properties of the LaFe_{11.14}Co_{0.66}Si_{1.2-x}Ga_{x} (where x=0.1, 0.2, 0.3) alloys, were investigated. It was revealed that increase of Ga content in the alloy composition causes the rise of lattice parameter of the La(Fe,Si)_{13}-type phase, which causes increase of the Curie temperature. However, the increase of Ga addition leads to decrease of magnetocaloric effect.
13
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Structural and Magnetocaloric Study οf the LaFe_{11.0}Co_{0.8}(Si_{0.4}Al_{0.6})_{1.2} Alloy

46%
Gębara P., Pawlik P., Škorvánek I., Marcin J., Wysłocki J.
|
|
issue 5
910-912
EN
In this study, we have investigated the microstructure and magnetic entropy change of annealed LaFe_{11.0}Co_{0.8}(Si_{0.4}Al_{0.6})_{1.2} alloy in a form of bulk samples and melt-spun ribbons. The bulk samples were annealed at 1323 K for 20 and 49 days and the maximum values of the magnetic entropy change | ΔS_M | obtained after the change of external magnetic field from 0 to 5 T reached 7.5 J kg^{-1} K^{-1} and 7.7 J kg^{-1} K^{-1}, respectively. For the melt-spun ribbon annealed at the same temperature for 1 h, the maximum value of | ΔS_M | reaches 4.5 J kg^{-1} K^{-1}. The temperature corresponding to the maximum entropy change increased from 292 K for bulk samples to 295 K for melt-spun ribbons. The lower values of the magnetic entropy change in the melt-spun LaFe_{11.0}Co_{0.8}(Si_{0.4}Al_{0.6})_{1.2} are attributed to the presence of higher volume fraction of the secondary bcc-Fe phase in the ribbon samples.
14
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Magnetic Properties of SMC Cores Produced at a Low Compacting Temperature

46%
Jakubas A., Gębara P., Seme S., Gnatowski A., Chwastek K.
Acta Physica Polonica A
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2017
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vol. 131
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issue 5
1289-1293
EN
Soft magnetic composites are readily used in the design of electromagnetic converters and electrical machines. In the paper, the magnetic properties of "home-made" cores made of iron powder and suspense polyvinyl chloride are examined. Samples were prepared by hot pressing of a PVC/Fe powder mixture with a different ratio of constituent components. Phase composition was investigated using an X-ray diffractometer and the presence of α-Fe was detected. Measurements of magnetic permeability revealed its allometric decrease with an increase of PVC content in composite. For the description of magnetization curves the phenomenological Jiles-Atherton model is used. The results of simulations are in a qualitative agreement with experiment.
15
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Magnetization Reversal Processes in Nanocrystalline (Pr, Dy)-(Fe, Co)-B Bulk Alloys

46%
Przybył A., Pawlik K., Pawlik P., Gębara P., Wysłocki J.
Acta Physica Polonica A
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2015
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vol. 127
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issue 2
579-581
EN
The aim of this paper was to study the phase constitution, magnetic properties and magnetization reversal processes in the rapidly solidified bulk (Pr,Dy)-(Fe,Co)-B alloys doped with Zr, Ti, Mn and Ni. The 3 mm outer diameter tubes samples of the Pr₈Dy₁Fe₆₀Co₇Ni_{(6x)}MnₓB₁₄Zr₁Ti₃ (where x = 0, 3, 6) alloys were produced by suction-casting technique. The admixture of Zr was introduced in order to improve their glass forming abilities while Dy was substituted to enhance the magnetocrystalline anisotropy of hard magnetic phase. The effect of Ni and Mn addition on the phase constitution and magnetic properties was studied in the presented work.
16
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Magnetic Properties and Structure after Crystallization of Fe_{80-x}B_{20}Nb_{x} (x=4, 6, 10) Metallic Glasses

46%
Nowosielski R., Kądziołka-Gaweł M., Gębara P., Szyba D., Babilas R.
Acta Physica Polonica A
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2017
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vol. 131
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issue 5
1212-1216
EN
The ferromagnetic Fe-based amorphous alloys were studied due to properties for soft magnetic applications. Depending on different Nb addition, the formation of crystalline phases after annealing of amorphous Fe_{80-x}B₂₀Nb_{x} (x = 4,6,10) alloys was studied. The crystallization products as well as the phase structure were determined using the Mössbauer spectrometry combined with differential scanning calorimetry and magnetic measurements. The addition of Nb caused a shift of crystallization process towards higher temperatures and induced changes in coercive force and decreased the saturation magnetization. It was found that Nb addition changed the crystallization process from single crystallization for Fe₇₆B₂₀Nb₄ alloy to binary crystallization in the Fe₇₄B₂₀Nb₆ and Fe₇₀B₂₀Nb₁₀ glasses. The annealing process at the onset crystallization temperature induced complex phase formation including the α-Fe, Fe₃B, and Fe₂B phases for alloys x=4, 6.
17
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Investigations of the Magnetization Reversal Processes in Nanocrystalline Nd-Fe-B Alloys Doped by Nb

39%
Kaźmierczak M., Pawlik P., Wysłocki J., Wnuk I., Gębara P., Pawlik K., Przybył A.
Acta Physica Polonica A
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2017
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vol. 131
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issue 4
789-791
EN
In the following article the magnetic properties and phase composition of (Nd₁₀Fe₆₇B₂₃)_{100-x}Nb_{x} (where x=5, 6, 7, 8, 9) alloys in the form of ribbons are discussed. The X-ray diffraction studies revealed the coexistence of amorphous and nanocrystalline structures consisting of Nd₂Fe₁₄B, Nd_{1+ε}Fe₄B₄ and metastable Nd₂Fe₂₃B₃ phases. The shape of M_{rev} (M_{irr}) suggests that the magnetization reversal proceeds through the nucleation of the reversal domain for the ribbon doped with 5-7 at.% of Nb and the subsequent pinning of the domain walls for ribbons doped with 8 and 9 at.% of Nb.
18
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Phase Composition and Magnetic Properties of the Nanocrystalline Fe_{64.32}Pr_{9.6}B_{22.08}W_{4} Alloy

39%
Filipecka K., Pawlik K., Pawlik P., Wysłocki J., Gębara P., Przybył A.
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vol. 126
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issue 1
164-165
EN
The aim of the present work was to study the influence of annealing conditions on magnetic properties and the phase constitution of rapidly solidified Fe_{64.32}Pr_{9.6}B_{22.08}W_{4} alloy ribbons. The base alloy was prepared by arc-melting of the high purity elements under an Ar atmosphere. Subsequently the ribbon samples were obtained by melt-spinning technique under low pressure of Ar. In order to develop nanocrystalline structure, the samples were annealed at 1003 K for 5, 10, 20 and 30 min. The room temperature magnetic properties were determined from hysteresis loops measured by VSM magnetometry in the external magnetic field up to 2 T. For comparison the influence of annealing temperature on magnetic properties was studied for the same alloy composition. The ribbons were annealed at temperatures from 929 K to 1023 K for 5 min. X-ray diffractometry was used to determine the phase composition of annealed ribbons. Heat treatment resulted in an evolution of the phase constitution, that caused changes in magnetic properties of the alloy.
19
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Magnetic Properties and Phase Constitution of the Nanocrystalline (Nd_{10}Fe_{67}B_{23})_{100-x}Nb_{x} (where x=1, 2, 3, 4) Alloy Ribbons

39%
Kaźmierczak M., Pawlik K., Pawlik P., Gębara P., Przybył A., Wysłocki J.
Acta Physica Polonica A
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2015
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vol. 128
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issue 1
91-93
EN
In the present work the magnetic properties and phase constitution of (Nd_{10}Fe_{67}B_{23})_{100-x}Nb_{x} (where x=1, 2, 3, 4) alloys in a form of ribbons were investigated. The ribbon samples were obtained by controlled atmosphere melt-spinning technique. In order to generate the nanocrystalline microstructure, ribbons were annealed at various temperatures (from 923 K to 1023 K) for 5 min. Subsequent annealing resulted in an evolution of the phase constitution accompanied by a change of their magnetic properties. The X-ray diffraction studies show presence of hard magnetic Nd_{2}Fe_{14}B, paramagnetic Nd_{1+ε }Fe_{4}B_{4} and ferromagnetic metastable Nd_{2}Fe_{23}B_{3} phases. The best hard magnetic parameters were measure for annealed ribbons of the (Nd_{10}Fe_{67}B_{23})_{96}Nb_{4} alloy.
20
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Effect of Tungsten Addition on Phase Constitution and Magnetic Properties of the Bulk Fe_{65}Pr_{9}B_{26-x}W_x Alloys

39%
Filipecka K., Pawlik P., Pawlik K., Gębara P., Przybył A., Pruba M.
Acta Physica Polonica A
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2015
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vol. 128
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issue 1
104-106
EN
The effect of tungsten addition on phase constitution and magnetic properties of the bulk Fe_{65}Pr_9B_{26-x}W_{x} (where x=2, 4, 6, 8) alloys was studied. The base alloys were prepared by arc-melting of the high purity elements under Ar atmosphere. Samples were produced by suction of an arc-molten alloy to a water-cooled copper mould (the suction-casting method). In order to develop nanocrystalline structure, the samples were subjected to annealing. Heat treatment resulted in an evolution of the phase constitution that caused changes in magnetic properties of the alloys. X-ray diffractometry was used to determine the phase composition of annealed samples. The analysis showed presence of hard magnetic Pr_2Fe_{14}B, paramagnetic Pr_{1+x}Fe_4B_4 and soft ferromagnetic α-Fe phases of annealed samples. The room temperature magnetic properties were determined from hysteresis loops measured by VSM magnetometer in the external magnetic field up to 2 T. The highest hard magnetic parameters were measured for the rod sample of Fe_{65}Pr_9B_{20}W_6 annealed at 1003 K for 5 min.
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