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Tytuł:
Magnetocaloric Effect of the $Tb_{1-x}Y_{x}NiAl$ and $TbNiAl_{1-y}In_{y}$ Series
Autorzy:
Kaštil, J.
Javorský, P.
Klicpera, M.
Powiązania:
https://bibliotekanauki.pl/articles/1534279.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
Opis:
We have studied the development of the magnetocaloric effect in the (Tb,Y)NiAl and TbNi(Al,In) series as determined from magnetization measurements. The transition from antiferromagnetic order in TbNiAl to ferromagnetic order in $Tb_{0.7}Y_{0.3}NiAl$ is accompanied by increase of the maximum entropy change from - 4.1 to - 4.4 J $kg^{-1} K^{-1}$. In the TbNi(Al,In) series, the change of uniaxial anisotropy in TbNiAl to the easy-plane anisotropy in TbNiIn leads to broadening of the magnetocaloric effect accompanied with large increase of the relative cooling power from 66 to 120 J $kg^{-1}$.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 888-890
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetocaloric Effect in Ni-Cu-Mn-Gd-Ga Alloy. XI Symposium of Magnetic Measurements
Autorzy:
Sielicki, K.
Wróblewski, R.
Leonowicz, M.
Powiązania:
https://bibliotekanauki.pl/articles/1402340.pdf
Data publikacji:
2015-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
Opis:
The magnetocaloric effect of the Ni-Cu-Mn-Gd-Ga polycrystalline alloy was investigated. The nominal composition of the alloy was $Ni_{50}Cu_{6.25}Mn_{16.75}Ga_{25}Gd_{2}$ at.%. The X-ray diffraction studies revealed presence of two phases at room temperature. This was confirmed by magnetic measurements conducted in low field of 4 kA/m (50 Oe), which showed two Curie transition temperatures, one in vicinity and the other one well above the room temperature. The analysis of isothermal magnetic curves allowed the calculation of magnetic entropy change ($\Delta S_{M}$). Although the peak value of $| \Delta S_{M}|$ is relatively low, ≈1.1 J/(kg K), it is very broad. The adiabatic temperature change (ΔT) measured near room temperature is ≈0.49 K. Such result is irrespective of the magnetizing-demagnetizing cycle frequency which varied from 2/min to 10/min.
Źródło:
Acta Physica Polonica A; 2015, 128, 1; 120-122
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Comparative Studies of Magnetocaloric Effect in Ni-Mn-Cu-Ga and Ni-Mn-Pb-Ga Alloys
Autorzy:
Sielicki, K.
Wróblewski, R.
Leonowicz, M.
Powiązania:
https://bibliotekanauki.pl/articles/1388040.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
Opis:
Effect of Pb substitution for Cu on magnetocaloric properties of $Ni₂Mn_{1-x}Cu_xGa$ (x = 0.25, 0.27, 0.29) alloy was investigated experimentally. The magnetic measurements of Ni-Mn-Pb-Ga alloys conducted at low field of 4kA/m (50 Oe) showed that their Curie points are above the room temperature (RT). The analysis of isothermal magnetic curves allowed the estimation of magnetic entropy change $(ΔS_{M})$. The highest calculated value of $|ΔS_{M}|,$ ≈ 12 J/(kgK) and ≈ 1.8 J/(kgK), was registered for alloys containing 6.25 at.% of Cu and 6.75 at.% of Pb, respectively. The adiabatic temperature changes (ΔT) measured near RT are ≈ 0.4 K.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 644-646
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetocaloric effect in antiferromagnetic half-Heusler alloy DyNiSb
Autorzy:
Synoradzki, K.
Ciesielski, K.
Kaczorowski, D.
Powiązania:
https://bibliotekanauki.pl/articles/1050664.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ee
75.30.Sg
Opis:
The low-temperature magnetic, thermal and magnetocaloric properties of the half-Heusler compound DyNiSb were studied on polycrystalline samples. The temperature variations of the magnetization and the heat capacity revealed a phase transition from paramagnetic to antiferromagnetic state at the Néel temperature T_{N} = 3.1 K. The compound exhibits normal and inverse magnetocaloric effect with the isothermal magnetic entropy change reaching 5.2 J/(kg K) at 4.8 K for a magnetic field change of 3 T. The estimated refrigerant capacity is about 58 J/kg.
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 691-693
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigations of the magnetization reversal processes in nanocrystalline Nd-Fe-B alloys doped by Nb
Autorzy:
Kaźmierczak, M.
Pawlik, P.
Wysłocki, J.
Wnuk, I.
Gębara, P.
Pawlik, K.
Przybył, A.
Powiązania:
https://bibliotekanauki.pl/articles/1052622.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.50.Bb
Opis:
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.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 789-791
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of Critical Behavior in Gd₇₅Ge₁₅Si₅Ce₅ Alloy
Autorzy:
Gębara, P.
Hasiak, M.
Powiązania:
https://bibliotekanauki.pl/articles/1055116.pdf
Data publikacji:
2017-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.50.Bb
Opis:
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.
Źródło:
Acta Physica Polonica A; 2017, 131, 5; 1232-1235
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural and Magnetocaloric Study οf the $LaFe_{11.0}Co_{0.8}(Si_{0.4}Al_{0.6})_{1.2}$ Alloy
Autorzy:
Gębara, P.
Pawlik, P.
Škorvánek, I.
Marcin, J.
Wysłocki, J.
Powiązania:
https://bibliotekanauki.pl/articles/1534407.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.50.Bb
Opis:
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.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 910-912
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Partial Substitution of Fe by Mn on the Thermomagnetic Properties of Magnetocaloric $LaFe_{11.2}Co_{0.7}Si_{1.1}$ Alloy
Autorzy:
Gębara, P.
Marcin, J.
Powiązania:
https://bibliotekanauki.pl/articles/1397028.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.50.Bb
Opis:
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.
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 648-650
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
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
Autorzy:
Gębara, P.
Powiązania:
https://bibliotekanauki.pl/articles/1398280.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.50.Bb
Opis:
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.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 798-800
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetocaloric Cooling Device with Reciprocating Motion of the Magnetic Field Source
Autorzy:
Kolano, R.
Kolano-Burian, A.
Hreczka, M.
Polak, M.
Szynowski, J.
Tomaka, W.
Powiązania:
https://bibliotekanauki.pl/articles/1398974.pdf
Data publikacji:
2016-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.50.Ww
Opis:
This paper describes the magnetic cooling device model designed and built at the Institute of Non-Ferrous Metals in Gliwice, which utilizes reciprocating motion of a magnetic field source and a cyclic flow of a coolant through regenerator. The regenerator made from gadolinum made it possible to obtain an adiabatic temperature change of 2.5 K at the magnetic field of 0.8 T. The magnetic field source was built using neodymium magnets according to our own technology. For the heat transfer, a liquid having the specific heat of about 4000 J/(kg K) has been applied. We have also developed and applied a special driving system enabling reciprocating motion of the magnetic field source and of the pistons in the hot and cold heat exchangers. The tests were made with this cooling model showing that it was possible to obtain, at the frequency of 0.5 Hz, the liquid temperature gradient of 4 K. The potential energy savings resulting from application of this device have been evaluated and compared with the literature data presenting a pre-industrial prototype of the magnetic refrigerator utilizing similar solutions to those applied in our cooling model.
Źródło:
Acta Physica Polonica A; 2016, 129, 6; 1205-1209
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Origin of Magnetic Anisotropy of $Gd_{5}Si_{2}Ge_{2}$ Compound
Autorzy:
Szymczak, R.
Kolano, R.
Kolano-Burian, A.
Hawelek, L.
Krzymanska, B.
Aleshkevich, P.
Dyakonov, V.
Szymczak, H.
Powiązania:
https://bibliotekanauki.pl/articles/1428706.pdf
Data publikacji:
2012-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Gw
75.30.Sg
Opis:
The second-order anisotropy constant $K_2$ in polycrystalline $Gd_5Si_2Ge_2$ giant magnetocaloric material was measured as a function of temperature by the modified singular point detection technique. Although the structural, electrical, thermal, magnetic and magnetocaloric properties of the $Gd_5Si_2Ge_2$ have been rather well investigated experimentally, magnetic anisotropy of this system is almost unknown. The singularity indicating the anisotropy field was determined analyzing ac susceptibility data taking into account several features of the magnetization curve. The temperature dependence of the anisotropy fields was measured from 4.2 K up to the Curie temperature. The observed relationship between $K_2 (T)//K_2$ (0) and magnetization M (T)/M (0) was explained assuming dipolar origin of magnetic anisotropy of $Gd_5Si_2Ge_2$ compound.
Źródło:
Acta Physica Polonica A; 2012, 121, 5-6; 1261-1262
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
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
Autorzy:
Gębara, P.
Pawlik, P.
Michalski, B.
Wysłocki, J.
Kotynia, K.
Powiązania:
https://bibliotekanauki.pl/articles/1402328.pdf
Data publikacji:
2015-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.50.Bb
Opis:
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.
Źródło:
Acta Physica Polonica A; 2015, 128, 1; 87-90
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetocaloric Effect in Geometrically Frustrated Magnetic Compound $HoB_{12}$
Autorzy:
Snyman, J.
Flachbart, K.
Gabani, S.
Reiffers, M.
Shitsevalova, N.
Siemensmeyer, K.
Strydom, A.
Powiązania:
https://bibliotekanauki.pl/articles/1534216.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.40.Cx
Opis:
The magnetocaloric effect of frustrated antiferromagnetic $HoB_{12}$ is calculated. The isothermal entropy change Δ S characterising the magnetocaloric effect shows a small positive change upon magnetisation below the transition temperature $T_{N}$, indicating a small inverse magnetocaloric effect. At $T_{N}$, Δ S shows clear scaling behaviour with the applied magnetic field. The adiabatic temperature change Δ T shows paramagnetic behaviour above $T_{N}$, despite strong magnetic correlations that persist in this temperature region. The adiabatic temperature change calculated for $HoB_{12}$ is appreciable.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 873-874
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
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
Autorzy:
Gębara, P.
Pawlik, P.
Michalski, B.
Wysłocki, J.
Powiązania:
https://bibliotekanauki.pl/articles/1387211.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.50.Bb
Opis:
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.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 576-578
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
About the Role of Fe-Ions in the Formation of Magnetocaloric Effect in $Ho(Co_{1-x}Feₓ)₂$ Compounds
Autorzy:
Anikin, M.
Tarasov, E.
Kudrevatykh, N.
Osadchenko, V.
Zinin, A.
Powiązania:
https://bibliotekanauki.pl/articles/1387987.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.50.Gg
Opis:
A study of crystalline structure, magnetic and magnetocaloric properties of $Ho(Co_{1-x}Feₓ)₂$ (x = 0.09, 0.12) intermetallic compounds has been undertaken. Phase composition was controlled by X-ray diffraction analysis. Magnetic properties were measured within the temperature range 4.2-350 K in magnetic fields up to 7 T. Magnetic ordering temperatures corresponding to paramagnetic-ferrimagnetic phase transitions were found to be 199 K and 258 K respectively. Temperature dependences of heat capacity for these compounds have been inferred for the temperature interval 77-340 K. Comparison of magnetocaloric effect (MCE) values determined by direct measurement and by calculation was carried out as well. It was found that significant MCE peak broadening occurs for higher iron concentration in the compound.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 635-637
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental Study of Magnetocaloric Effect in Dipolar Magnet $KEr(MoO_4)_2$
Autorzy:
Hanko, J.
Orendáč, M.
Kajňaková, M.
Orendáčová, A.
Feher, A.
Powiązania:
https://bibliotekanauki.pl/articles/1813812.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.50.Ee
Opis:
We report on magnetothermodynamic properties of single crystal $KEr(MoO_4)_2$ which were investigated from nominally 0.4 K to 20 K in magnetic fields up to 4 T. Using the available specific heat data the diagram of temperature and magnetic field dependence of the total entropy was constructed. Predictions for temperature dependences of the relative temperature variations during the adiabatic demagnetization and the entropy variation during the isothermal demagnetization were calculated from the specific heat data. The obtained results suggest that unlike common refrigerants, in $KEr(MoO_4)_2$ the quantities describing magnetic cooling remain nearly constant in the temperature range 2-10 K.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 465-468
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Fe addition on the martensitic transformation, structure and magnetic properties of metamagnetic Ni-Co-Mn-Sn alloys
Autorzy:
Wójcik, A.
Maziarz, W.
Szczerba, M.
Sikora, M.
Hawełek, Ł.
Czaja, P.
Powiązania:
https://bibliotekanauki.pl/articles/1154400.pdf
Data publikacji:
2016-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
81.30.Kf
Opis:
In this study the effect of Fe for Ni substitution in Ni₄₄Co₆Mn₃₉Sn₁₁ metamagnetic shape memory alloys on their structure, magneto-structural transformation characteristics, magnetic and magnetocaloric properties was studied. The results show that the structure and martensite transformation behavior strongly depends on the Fe concentration. The martensitic transformation temperature decreases with 1 at.% of Fe and is suppressed with higher Fe content. It was further found that substitution of Fe for Ni leads to lowering of the value of magnetic entropy change.
Źródło:
Acta Physica Polonica A; 2016, 130, 4; 1026-1028
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Properties and Magnetocaloric Effect οf $R_{1-x}R_{x}Mn_{2}Ge_{2}$ Compounds
Autorzy:
Duraj, M.
Szytuła, A.
Powiązania:
https://bibliotekanauki.pl/articles/1538438.pdf
Data publikacji:
2010-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Kz
75.30.Sg
Opis:
The magnetic and magnetocaloric properties of $Sm_{1-x}Gd_{x}Mn_{2}Ge_{2}$ compounds with 0 ≤ x ≤ 0.10 have been studied. $SmMn_{2}Ge_{2}$ is antiferromagnetic below the Néel temperature $T_{N}$ ( ≈ 400 K). Further cooling leeds to canted ferromagnetic phase below $T_C$ = 341 K. With decreasing temperature, two metamagnetic phase transitions are observed: F2-AF1 at $T_2$ = 153 K and AF1-F1 at $T_1$ = 106 K. The maximum values of magnetic entropy change | Δ $S_m$ | are found to be 1.5 J $K^{-1} kg^{-1}$ at $T_{1}$ and 2.0 J $K^{-1} kg^{-1}$ at $T_{2}$ in $SmMn_{2}Ge_{2}$. The MCE is found to increase with Gd concentration, | Δ $S_{m}(T_{1})$ | = 3.3 J $K^{-1} kg^{-1}$, while | Δ $S_{m}(T_{2})$ | is slightly enhanced for x = 0.1. The magnetocaloric effect is found to be positive at $T_{1}$ and negative at $T_{2}$.
Źródło:
Acta Physica Polonica A; 2010, 117, 4; 603-606
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Entropy Change Calculations for Pure Gd and a Ni-Mn-Cu-Ga Heusler Alloy: Constant Field vs. Constant Temperature Experiment
Autorzy:
Ferenc, J.
Kowalczyk, M.
Wróblewski, R.
Cieślak, G.
Sielicki, K.
Leonowicz, M.
Kulik, T.
Powiązania:
https://bibliotekanauki.pl/articles/1402338.pdf
Data publikacji:
2015-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
65.40.gd
Opis:
The magnetocaloric effect may be assessed indirectly by expressing it as the change in magnetic entropy in varying magnetic field, H, as the function of temperature, T. Magnetization, M=f(T,H), may be experimentally acquired from a series of isothermal measurements with variable field, or from a series of constant field measurements with variable temperature. The accuracy of magnetic entropy calculation depends on the number of series in these experiments. The aim of this work is to determine how little data is sufficient to obtain accurate results of magnetic entropy change calculations, on the basis of real, magnetocaloric materials. Pure gadolinium and a Ni-Mn-Cu-Ga Heusler alloy were studied. For both materials, the magnetic entropy change and relative cooling power were calculated from both experiments, with the decreasing number of experimental data. For both materials, the constant field experiment with only 6 field values provided only a 5% error of calculations, as compared to the experiment with 100 field values. The Arrott plots were also drawn for constant field mode with 6 field values, easily indicating the order of transition. Comparison of the calculation results suggests that the constant field mode magnetization measurement may be more accurate and faster than isothermal mode.
Źródło:
Acta Physica Polonica A; 2015, 128, 1; 111-115
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
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
Autorzy:
Gębara, P.
Powiązania:
https://bibliotekanauki.pl/articles/1398815.pdf
Data publikacji:
2016-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.50.Bb
Opis:
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.
Źródło:
Acta Physica Polonica A; 2016, 129, 2; 193-196
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental Investigation of Small-Scale Magnetocaloric Refrigerator
Autorzy:
Kaštil, J.
Tětek, J.
Tuček, A.
Powiązania:
https://bibliotekanauki.pl/articles/1399319.pdf
Data publikacji:
2013-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.50.Ww
Opis:
The small-scale magnetocaloric cooling device was developed at Czech Technical University in Prague. The magnetocaloric small-scale cooling system was designed as push-pull system with two permanent magnets with field of about 0.85 T. The construction offers a possibility to alter independently many parameters of the cooling process and it ensures easy way to change working material and design of heat exchangers. The measurements were performed with 35 g of gadolinium as a working material and ethanol as heat transfer liquid. Device was successfully operated at room temperature with maximal heat span of 3.1 K. In the article we report design of the machine and first measurement performed on it.
Źródło:
Acta Physica Polonica A; 2013, 124, 4; 740-744
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Influence of Alloy Admixture on Structure and Properties of rm $La(Fe, Co, Si)_{13}$-Type Phase
Autorzy:
Gębara, P.
Pawlik, P.
Škorvánek, I.
Marcin, J.
Wysłocki, J.
Szwaja, M.
Pawlik, K.
Powiązania:
https://bibliotekanauki.pl/articles/1429027.pdf
Data publikacji:
2012-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.50.Bb
Opis:
In the present study, the influence of Al and Ga admixture on the lattice parameters and the Curie point $T_{C}$ of the $La(Fe, Co, Si)_{13}$ compound was discussed. The measurements were carried out on ribbon samples of $LaFe_{11.0}Co_{0.8}Si_{1.2},$ $LaFe_{11.0}Co_{0.8}(Si_{0.4}Al_{0.6})_{1.2}$ and $LaFe_{11.0}Co_{0.8}Si_{1.1}Ga_{0.1}$ alloys. The samples were subjected to annealing in the inert gas atmosphere at 1323 K for 24 h. The change of lattice parameters a with admixture of Al and Ga was determined from the X-ray diffraction analysis. Furthermore, changes of the Curie point with the alloy composition were observed.
Źródło:
Acta Physica Polonica A; 2012, 121, 5-6; 1285-1287
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Si Substitution and Annealing on Magnetocaloric Properties in $TbCo_2$
Autorzy:
Janatova, M.
Poltierova Vejpravova, J.
Javorsky, P.
Prokleska, J.
Svoboda, P.
Danis, S.
Powiązania:
https://bibliotekanauki.pl/articles/1813663.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
65.40.Gd
75.30.Sg
Opis:
We report on magnetocaloric properties of the as-cast and annealed $TbCo_2$ with partial substitution of cobalt by silicon. The samples were characterized by powder X-ray diffraction and investigated by heat capacity measurements (8-300 K, in fields 0 T and 1 T). $TbCo_2$ undergoes a second-order type phase transition at $T_C$ = 240 K, from paramagnetic to ferrimagnetic state;similar behavior was revealed in the Si-doped compounds. The temperature dependence of magnetic entropy and the corresponding magnetocaloric effect were derived for all studied samples. The influence of the heat treatment and Si doping on magnetocaloric properties will be discussed in context of the analogue case $Er(Co_{1-x}Si_x)_2$.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 311-314
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Phase Transitions and Thermal Properties of $Ho(Co_{1-x}Si_x)_2$ Compounds
Autorzy:
Vasylyev, D.
Prokleška, J.
Sechovský, V.
Powiązania:
https://bibliotekanauki.pl/articles/1813682.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.50.Gg
Opis:
The specific heat of $HoCo_2$ and $Ho(Co_{0.95}Si_{0.05})_2$ was measured as a function of temperature in several constant magnetic fields up to 8 T. A data analysis allowed us to determine the isothermal entropy change and the magnetocaloric effect in a wide temperature range. The considerable values of the magnetocaloric effect in the vicinity of the magnetic ordering transition are qualifying both compounds as suitable for magnetic refrigeration purposes. The magnetic phase transition temperature $(T_C)$ increases from 77 K for $HoCo_2$ to 103 K for $Ho(Co_{0.95}Si_{0.05})_2$ while the large magnetocaloric effect in the vicinity of TC is maintained, which demonstrates possible ways of tuning the operating temperatures of the magnetic refrigerant.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 347-350
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetocaloric Study of S=1/2 Low-Dimensional Heisenberg Antiferromagnet $[Cu\text{(phen)}(H_2O)_2]SO_4$
Autorzy:
Sedláková, L.
Orendáč, M.
Kajňaková, M.
Orendáčová, A.
Feher, A.
Powiązania:
https://bibliotekanauki.pl/articles/1813815.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.50.Ee
Opis:
We present the experimental study of magnetocaloric effect on powder sample $[Cu\text{(phen)}(H_2O)_2]SO_4$ (phen = phenantroline = $C_{12}H_8N_2$) in the temperature range from nominally 0.2 K to 4 K and in magnetic fields up to 2 T. The values of total entropy were extracted from the experimental data obtained by adiabatic demagnetization. The comparison was performed with the temperature dependence of the entropy for S=1/2 paramagnet calculated at selected magnetic fields. The deviations observed below 0.6 T were attributed to internal field mediated by exchange coupling. In addition, the temperature response observed in $[Cu\text{(phen)}(H_2O)_2]SO_4$ revealed very short relaxation time below 1 K. The comparison of the behavior observed at the end of the demagnetization in $[Cu\text{(phen)}(H_2O)_2]SO_4$ and other systems suggests that the magnetocaloric effect can serve as an alternative tool for studying slow magnetic relaxation.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 473-476
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Remark about an Analogy between Magnetocaloric Behaviour of Type II Superconductors and Ferromagnetic Materials
Autorzy:
Kalva, Z.
Mánek, P.
Powiązania:
https://bibliotekanauki.pl/articles/2013015.pdf
Data publikacji:
2000-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
74.60.Ge
Opis:
The analogy between magnetocaloric behaviour of type II superconductors and anisotropic ferromagnetic materials is discussed. Special attention is devoted to the influence of anisotropy on the negative magnetocaloric effect near phase transitions.
Źródło:
Acta Physica Polonica A; 2000, 97, 3; 407-410
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermomagnetic Properties of $LaFe_{11.0}Co_{0.8}(Si_{1-x}Al_{x})_{1.2}$ (x=0, 0.6) Alloys
Autorzy:
Gębara, P.
Pawlik, P.
Skorvanek, I.
Marcin, J.
Pawlik, K.
Przybył, A.
Wysłocki, J.
Szwaja, M.
Filipecka, K.
Powiązania:
https://bibliotekanauki.pl/articles/1367677.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.50.Bb
Opis:
In the present work, Curie temperature, refrigeration capacity and cooling power of the $LaFe_{11.0}Co_{0.8}(Si_{1-x}Al_{x})_{1.2}$ (where x=0, 0.6) alloys, are investigated. The value of Curie temperature was found to be 280 and 290 K for x=0 and 0.6, respectively. The determined values of cooling power (RCP) and refrigeration capacity (RC) differ only slightly for both investigated alloys. The maximum values of RCP and RC obtained under the change of external magnetic field from 0 to 5 T are 433 J/kg (for x=0) and 290 J/kg (for x=0.6), respectively.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 166-167
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental Study of the Magnetocaloric Effect in the Two-Dimensional Quantum System $Cu(tn)Cl_2$
Autorzy:
Baranová, L.
Tarasenko, R.
Orendáčová, A.
Orendáč, M.
Pavlík, V.
Feher, A.
Powiązania:
https://bibliotekanauki.pl/articles/1368656.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ee
75.30.Sg
Opis:
Magnetocaloric studies of a two-dimensional antiferromagnet $Cu(tn)Cl_{2}$ (tn=1,3-diaminopropane=$C_3H_{10}N_2)$ have been performed by adiabatic magnetization and demagnetization measurements, in the temperature range from 0.2 to 4 K and magnetic fields up to 2 T. The compound represents an S=1/2 spatially anisotropic triangular-lattice antiferromagnet. The magnetocaloric measurements were focused at the identification of the phase transition to the magnetically ordered state which was not indicated in the previous specific heat studies. Furthermore, the interplay of the magnetic-field induced easy-plane anisotropy and the intrinsic spin anisotropy present in the studied system should manifest in low magnetic fields. The obtained results of the magnetocaloric experiments of $Cu(tn)Cl_{2}$ indicate a double crossover from the normal to inverse magnetocaloric effect (MCE). The first crossover from the normal to inverse MCE occurring at about 0.3 K can be attributed to the competition of the aforementioned anisotropies. The second crossover from the inverse to normal MCE observed at about 2.2 K might be ascribed to the formation of spin vortices stabilized by the easy-plane anisotropy introduced by magnetic field.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 256-257
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetocaloric effect in CsDy(MoO₄)₂
Autorzy:
Tarasenko, R.
Tkáč, V.
Orendáčová, A.
Orendáč, M.
Sechovský, V.
Feher, A.
Powiązania:
https://bibliotekanauki.pl/articles/1050647.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.30.Gw
71.70.Ej
Opis:
CsDy(MoO₄)₂ belongs to the family of binary alkaline rare-earth molybdates, with detectable low-temperature structural phase transitions, caused by the cooperative Jahn-Teller effect. Magnetocaloric studies of a single crystal of CsDy(MoO₄)₂ have been performed in the temperature range from 2 K to 18 K in magnetic fields up to 7 T applied along the crystallographic a axis. The maximum value of the isothermal entropy change is about 8 J/(kgK) and was achieved already in the fields above 2 T. The observed results suggest that the studied system can be used as a magnetic refrigerant at helium temperatures.
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 414-416
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Giant Magnetocaloric Effect in Manganites
Autorzy:
Szymczak, R.
Kolano, R.
Kolano-Burian, A.
Dyakonov, V.
Szymczak, H.
Powiązania:
https://bibliotekanauki.pl/articles/1550566.pdf
Data publikacji:
2010-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.47.Lx
75.30.Sg
75.40.Cx
Opis:
In this review we briefly discuss the magnetocaloric properties of the manganites. It is evidenced that the maximum entropy change observed in manganites exceeds that of gadolinium (the prototype material for room temperature refrigerators). For the manganites characterized by second-order magnetic phase transitions the scaling hypothesis is discussed. It is shown that simple phenomenological model with only one fitting parameter, presented in this paper, satisfactorily describes experimental observations.
Źródło:
Acta Physica Polonica A; 2010, 117, 1; 203-206
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetocaloric Effect and Transition Order in $HoAl_{2}$
Autorzy:
Baran, S.
Duraj, R.
Szytuła, A.
Powiązania:
https://bibliotekanauki.pl/articles/1399261.pdf
Data publikacji:
2015-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Cr
75.30.Kz
75.30.Sg
Opis:
Magnetic measurements of $HoAl_{2}$ are reported. The compound crystallizes in the cubic $MgCu_{2}$-type crystal structure. $HoAl_{2}$ exhibits two successive magnetic transitions: below $T_{c}$ = 29 K a ferromagnetic order is formed while anomaly at $T_{t}$ = 20 K is related to reorientation of magnetic moment. Near transition temperatures a magnetocaloric effect with magnetic entropy changes -$ΔS_{m}$ equal to 6.3 J/(mol K) at $T_{c}$ and 5.0 J/(mol K) at $T_{t}$ for an external field $μ_{0}H$ = 9 T is observed.
Źródło:
Acta Physica Polonica A; 2015, 127, 3; 815-817
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetocaloric Effect in $La_{0.8}Sr_{0.2}MnO_{3}$ Film
Autorzy:
Szymczak, R.
Dyakonov, K.
Radelytskyi, I.
Dyakonov, V.
Szymczak, H.
Powiązania:
https://bibliotekanauki.pl/articles/1402317.pdf
Data publikacji:
2015-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.47.Lx
75.70.Ak
Opis:
Thin epitaxial film of $La_{0.8}Sr_{0.2}MnO_{3}$ has been deposited on yz-cut $LiNbO_{3}$ by pulsed laser ablation. The film was characterized by X-ray diffraction and magnetic measurements as a single phase. The magnetic properties and the magnetocaloric effect have been measured as a function of magnetic field and temperature. A reasonably high magnetocaloric effect indicates that this film might provide an efficient material for micro magnetic refrigerators.
Źródło:
Acta Physica Polonica A; 2015, 128, 1; 56-58
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Power Losses in $LaFe_{x}Co_{y}Si_{1.1}$ Intermetallics near the Magnetic Phase Transition
Autorzy:
Gozdur, R.
Lebioda, M.
Bernacki, Ł.
Powiązania:
https://bibliotekanauki.pl/articles/1402334.pdf
Data publikacji:
2015-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.30.Kz
75.50.Bb
Opis:
The paper presents magnetic parameters of $LaFe_{x}Co_{y}Si_{1.1}$ bulk specimens proving strong magnetocaloric effect. The main research work was oriented on measurements of the alloy's power losses according to IEC 60404 standards and validated with unbalanced bridge method and other methods. The measurements of the $LaFe_{10.8}Co_{1.1}Si_{1.1}$ specimens were determined in the range of temperatures near the Curie temperature where the magnetocaloric effect is the strongest. Power losses were taken into account mainly for the evaluation of usefulness and efficiency in the magnetic refrigeration applications. The results of presented measurements testify that the most suitable range of temperature and the best operational conditions are very close to the point of magnetic phase transition and slightly above it. It indicates that the magnetic state between the $T_{ \Delta S max}$ and $T_{c}$ is more effective for the magnetic refrigeration applications due to lower power losses and high level of the isothermal changes of entropy. Operating temperature below the $T_{ \Delta S max}$ in ferromagnetic state is improper because of the increasing power losses which achieve the level of 130 mJ/kg for main frequency and decrease to 20 mJ/kg for the value of 0.1 Hz.
Źródło:
Acta Physica Polonica A; 2015, 128, 1; 98-103
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Low-Temperature Specific Heat and Magnetocaloric Effect in $RCu_2Ge_2$ (R = Dy-Tm) Compounds
Autorzy:
Gondek, Ł.
Kaczorowski, D.
Pikul, A.
Szytuła, A.
Powiązania:
https://bibliotekanauki.pl/articles/1419609.pdf
Data publikacji:
2012-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.-m
75.30.Sg
75.40.Cx
Opis:
The magnetocaloric effect in $RCu_2Ge_2$ (R = Dy-Tm) was investigated by means of specific heat measurements. The compounds order antiferromagnetically at 6.2 K $(DyCu_2Ge_2),$ 5.6 K $(HoCu_2Ge_2),$ 3.0 K $(ErCu_2Ge_2),$ and 3.9 K $(TmCu_2Ge_2),$ and some of them exhibit additional magnetic transitions in the ordered state. In an external magnetic field the low-temperature specific heat changes significantly, which can be attributed to metamagnetic-like transitions. In this temperature region, the investigated samples show distinctly different magnetocaloric effect.
Źródło:
Acta Physica Polonica A; 2012, 122, 2; 391-393
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Specific Heat of the $Tb_{1-x}La_xNi_2$ Solid Solutions
Autorzy:
Ćwik, J.
Palewski, T.
Nenkov, K.
Powiązania:
https://bibliotekanauki.pl/articles/1813679.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.40.-s
74.70.Ad
Opis:
Specific heat measurements have been performed on the polycrystalline $TbNi_2, LaNi_2$ and their solid solutions $Tb_{1-x}La_xNi_2$ (x=0.2, 0.3). The Debye temperatures, phonon and conduction electron contributions as well as the magnetic part of the heat capacity were determined and discussed. The magnetocaloric effect was estimated from measurements performed in a magnetic field of 0.42 T for $TbNi_2,$ $Tb_{0.8}La_{0.2}Ni_2$ and $Tb_{0.7}La_{0.3}Ni_2$.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 343-346
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Critical Behavior near the Ferromagnetic to Paramagnetic Phase Transition in Y₈Co₆₂B₃₀ Amorphous Alloy
Autorzy:
Śniadecki, Z.
Marcin, J.
Idzikowski, B.
Powiązania:
https://bibliotekanauki.pl/articles/1031033.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Cx
75.50.Kj
75.30.Sg
Opis:
The Y₈Co₆₂B₃₀ amorphous alloy is a collinear ferromagnet. The Arrott plot, the Kouvel-Fisher method, critical isotherm analysis and magnetic field dependence of maximum magnetic entropy changes were the main analytical tools used to determine the nature of the ferromagnetic/paramagnetic phase transition. Values of critical exponents (β, γ, and δ) were calculated and were convergent with those characteristic for mean-field model. It suggests that long range ferromagnetic interactions are playing main role in investigated alloy and the phase transition was confirmed to be of a second order according to the Banerjee criterion.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 967-969
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental Study of the Magnetocaloric Effect in Ni(en)(H₂O)₄SO₄·2H₂O - An S = 1 Molecular Magnet with Easy-Plane Anisotropy
Autorzy:
Tarasenko, R.
Orendáčová, A.
Čižmár, E.
Orendáč, M.
Potočňák, I.
Feher, A.
Powiązania:
https://bibliotekanauki.pl/articles/1032138.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.30.Gw
71.70.Ch
Opis:
Magnetocaloric properties of Ni(en)(H₂O)₄SO₄·2H₂O powder were investigated in temperature range from 2 K to 30 K in magnetic fields up to 7 T using isothermal magnetization measurements. The maximum value of the isothermal entropy change in the field 7 T is about 8 J/(kg K), with a refrigerant capacity of 55 J/kg. Temperature dependence of the isothermal entropy change under different magnetic fields is in good agreement with theoretical predictions from crystal electric field parameters.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 904-906
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetocaloric Effect in NiCl₂(bipy) at Low Temperatures
Autorzy:
Ráczová, K.
Čižmár, E.
Feher, A.
Powiązania:
https://bibliotekanauki.pl/articles/1032298.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.30.Gw
75.10.Pq
Opis:
Magnetothermal properties of the compound NiCl₂(bipy), where bipy = 4,4'-bipyridine, were studied. The single-ion anisotropy of Ni(II) ions was estimated and its influence on magnetocaloric effect in NiCl₂(bipy) was investigated. Above the metamagnetic transition a maximum in the isothermal change of the magnetic entropy is reached near 11 K at field change from 0T to 7T with peak value -ΔS = 6J K¯¹ kg¯¹. The temperature dependence of ΔS above 7K agrees with the assumed easy-axis type of single-ion anisotropy. The inverse magnetocaloric effect, typical for ordered antiferromagnets, was observed in the ordered state of NiCl₂(bipy) only for isothermal magnetization in small fields up to 2T.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 922-924
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The magnetocaloric effect in {[Cu(bapa)]₃[Cr(CN)₆]₂}ₙ · 6n H₂O at low temperatures
Autorzy:
Ráczová, K.
Vavra, M.
Hegedüs, M.
Čižmár, E.
Powiązania:
https://bibliotekanauki.pl/articles/1048121.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.30.Gw
75.10.Pq
Opis:
The crystals of {[Cu(bapa)]₃[Cr(CN)₆]₂}ₙ·6nH₂O (bapa = bis(3-aminopropyl)amine) are formed by infinite Cu(II)-Cr(III) antiparallel chains, which are connected into the third direction by additive [Cu(bapa)] moieties. The onset of long-range magnetic order at 3.2 K was observed by AC susceptibility. The study of the magnetocaloric effect from magnetization measurements yields a large entropy change -ΔS_{M} = 13.65 J K¯¹mol¯¹ (-ΔS_{M} = 12.25 J kg¯¹K¯¹) at the field change from 0 T to 3 T at temperature 4 K. The analysis of the critical behavior of -ΔS_{M} suggests the value of critical exponent n = 0.577 at the ordering temperature characteristic for three-dimensional magnets with Ising anisotropy.
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 429-431
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Scaling of anhysteretic curves for LaFeCoSi alloy near the transition point
Autorzy:
Gozdur, R.
Chwastek, K.
Najgebauer, M.
Lebioda, M.
Bernacki, Ł.
Wodzyński, A.
Powiązania:
https://bibliotekanauki.pl/articles/1053125.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.60.-d
75.60.Ej
Opis:
LaFeCoSi alloys have attracted much attention as they exhibit magnetocaloric effect in near room temperature. The paper focuses on the description of anhysteretic curve for LaFeCoSi alloy for temperatures close to transition point. For this purpose the Langevin function is applied. The paper confirms that the Langevin function might be a good starting point for development of analytical models aimed at examination of magnetic properties in La-based magnetocaloric materials.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 801-803
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic and structural studies into the effect of solvent exchange process in metal-organic framework MOF-76(Gd)
Autorzy:
Almáši, M.
Zeleňák, V.
Zeleňáková, A.
Powiązania:
https://bibliotekanauki.pl/articles/1054760.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.75.Fk
65.40.gd
Opis:
Effect of solvent exchange/absence on magnetic and structural properties of microporous metal-organic framework MOF-76(Gd) has been performed. Three compounds have been prepared and characterized: as synthesized MOF-76(Gd)-DMF, which containing DMF (N,N'-dimethylformamide) and H₂O molecules in the cavity system, activated complex without solvents, MOF-76(Gd) and water exchanged sample MOF-76(Gd)-H₂O. The structural study showed that compounds undergo structural changes after activation/exchange processes. Changes were mainly observed in the magnetic properties and distances between Gd...Gd ions: 4.718 Å for MOF-76(Gd)-DMF, 4.326 Å for MOF-76(Gd)-H₂O and 4.296 Å for MOF-76(Gd). The magnetic properties of the samples were studied by magnetic susceptibility χ_{M}(T) and magnetization M(H). The low positive value of the Weiss constant, Θ = 1.54 K in compound MOF-76(Gd)-DMF shows on a very weak ferromagnetic interaction. On the contrary, the negative values of Θ in complexes MOF-76(Gd) (-5.58 K) and MOF-76(Gd)-H₂O (-6.23 K) confirm the existence of antiferromagnetic exchange interaction between Gd(III) ions.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 991-993
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Scaling analysis of the magnetocaloric effect in Co/Au nanoparticles
Autorzy:
Hrubovčák, P.
Zeleňáková, A.
Zeleňák, V.
Franco, V.
Powiązania:
https://bibliotekanauki.pl/articles/1054838.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.75.Fk
65.40.gd
Opis:
The system of superparamagnetic Co/Au bimetallic nanoparticles of average diameter 7 nm was investigated with respect to its magnetocaloric properties. DC magnetic measurements revealed the presence of field dependent zero field cooled M(T) maximum (6-8 K) and significant zero field cooled/field cooled irreversibility at low temperatures in the system. Documented thermal hysteresis disallow standard magnetic entropy change calculation from isothermal M(H) data, thus we attempted to employ zero field cooled M(T) data for this purpose. Magnetic entropy change was calculated employing the Maxwell relation. In maximal field variation of 1 T relative high magnetic entropy change for nanoparticles Δ S_M ≈ 0.7 J/(kg K) at T =9 K was observed. The data collapsed onto single universal curve after proper axis rescaling.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 795-797
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic properties and flux distribution in the LaFeCoSi/FeCoV hybrid structure
Autorzy:
Gozdur, R.
Lebioda, M.
Najgebauer, M.
Powiązania:
https://bibliotekanauki.pl/articles/1055094.pdf
Data publikacji:
2017-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.30.Kz
75.50.Bb
Opis:
The study contains a description of magnetic properties of LaFeCoSi/FeCoV structure. The hybrid structure contains magnetocaloric LaFeCoSi core with high-induction ferromagnetic laminations. The magnetic field inside the magnetic structure is gained by the fringe field from FeCoV laminations. Results of modelling and experimental investigations of modified magnetic properties of LaFeCoSi/FeCoV structure were presented and discussed in the paper.
Źródło:
Acta Physica Polonica A; 2017, 131, 5; 1294-1297
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Production of $LaCaMnO_3$ Composite by Ball Milling
Autorzy:
Gencer, H.
Cengiz, N.
Kolat, V.
Izgi, T.
Atalay, S.
Powiązania:
https://bibliotekanauki.pl/articles/1207685.pdf
Data publikacji:
2014-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.20.Ev
75.47.Lx
75.30.Sg
Opis:
$La_{0.67}Ca_{0.33}MnO_3$ perovskite-type manganite was synthesized by high-energy ball milling raw oxides of $La_2O_3$ (purity 99.9%), $CaCO_3$ (purity > 99%), and MnO (purity > 99%). The ratio of ball and powder weight was 10:1 and the rotating speed was set to 500 rpm. X-ray analysis indicated that $La_{0.67}Ca_{0.33}MnO_3$ single phase was formed completely when milling time is up to 4 h. The peak intensity of perovskite structure decreased and a hump-like peak appeared with further milling time. When the milling time is longer than 40 h, the perovskite structure disappeared and the amorphous phase was formed completely. Scanning electron microscopy picture of 24 h milled sample showed that the particle size generally varies in a broad range from nanometer scale to a few μm. The magnetic measurements showed that ball milling samples have an inhomogeneous magnetic state and exhibit spin-glass like behavior. The significantly small magnetic entropy change and a remarkably broad temperature interval in entropy change were attributed to high degree of structural and magnetic disorder and broadening of magnetic transition.
Źródło:
Acta Physica Polonica A; 2014, 125, 2; 214-216
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Field Induced Unusual Magnetic Behavior at Low Temperature in $Pr_{0.67}Ca_{0.33}MnO_3$
Autorzy:
Pektas, M.
Gencer, H.
Izgi, T.
Kolat, V.
Atalay, S.
Powiązania:
https://bibliotekanauki.pl/articles/1207723.pdf
Data publikacji:
2014-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.47.Lx
75.30.Kz
75.30.Sg
Opis:
In this study, magnetic properties of $Pr_{0.67}Ca_{0.33}MnO_3$ compound were investigated in detail. The magnetization versus temperature (M-T) curve showed that this material undergoes a charge order transition at 200 K. A more pronounced FM phase appeared below 56 K. At T = 5 K, a field induced sharp step like magnetisation transition associated with phase separation was observed. However, after application of 7 T magnetic field at 5 K, the magnetic behaviour of sample was changed completely and full FM behaviour was observed. The more interesting is that the sample remains in the FM state and does not retrieve the initial magnetic state until warmed up to charge order transition temperature. Large negative magnetic entropy change (- 26.18 J/(kg K) at 38 K and 5 T) was attributed to step like magnetisation transition.
Źródło:
Acta Physica Polonica A; 2014, 125, 2; 217-219
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetocaloric Effect in Materials with the First Order Transitions - Direct Measurements
Autorzy:
Kamarád, J.
Kaštil, J.
Arnold, Z.
Javorský, P.
Sechovský, V.
Powiązania:
https://bibliotekanauki.pl/articles/1535138.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
75.30.Kz
75.50.Cc
Opis:
The results of direct measurements of the magneto-caloric characteristics Δ $T_{ad}$ and the indirect determination of Δ $S_{m}$ of pure Gd around the Curie temperature and of the $FeMnP_{0.45}As_{0.55}$ and $Ni_{45}Co_5Mn_{31}Ga_{19}$ intermetallics in the vicinity of the first order magnetic and structural phase transitions are presented and discussed. A pronounced temperature and field dependence of the first order transitions in the studied materials manifests restrictions applying these materials in magnetic refrigeration techniques. An effective use of the Ericsson and the Brayton refrigeration cycles with $FeMnP_{0.45}As_{0.55}$ in the role of a refrigerant is discussed.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 1000-1001
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Anisotropy of the Magnetocaloric Effect in the $Ni_{49.6}Mn_{27.6}Ga_{22.8}$ Single Crystal
Autorzy:
Wroblewski, R.
Sielicki, K.
Leonowicz, M.
Powiązania:
https://bibliotekanauki.pl/articles/1402315.pdf
Data publikacji:
2015-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
65.40.gd
75.30.Gw
75.30.Sg
Opis:
The magnetocaloric effect anisotropy in the $Ni_{49.6}Mn_{27.6}Ga_{22.8}$ single crystal was investigated. In the examined alloy the structural phase transition and magnetic transition occur at room temperature and around 370 K, respectively. The magnetic entropy change, at those two temperatures, was determined on the basis of isothermal and isofield curves, recorded at fields up to 1200 kA/m (1.5 T) with temperature steps of 2.5 and 5 K. Although the calculated values of magnetic entropy change are relatively small, ≈0.7 J/(kg K), an anisotropy of the magnetocaloric effect is observed with a magnetic field applied along the main crystallographic directions of the single crystal. The magnetic entropy change at the structural phase transition depends on the orientation. The weakest magnetocaloric effect occurs when the field is applied along [1 0 0] direction whereas the highest magnetocaloric effect value is reached along [0 0 1] direction, which is an easy magnetization axis. Such behaviour can be explained with the high magnetocrystalline anisotropy of the martensitic phase. The magnetic entropy change value, at the structural phase transition, obtained for the polycrystalline specimen, is close to that for the [0 0 1] single crystal direction.
Źródło:
Acta Physica Polonica A; 2015, 128, 1; 54-55
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
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