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254 results on '"Yapaskurt, V. O."'

20. Polymorphism and Isomorphic Substitutions in the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{Cu}}_{3}^{{2 + }}$$\end{document}(T5+O4)2 Natural System with T = As, V, or P

Author

Pekov, I. V., Zubkova, N. V., Yapaskurt, V. O., Koshlyakova, N. N., Turchkova, A. G., Sidorov, E. G., and Pushcharovsky, D. Yu.

Published
2020
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32. Magnetic and magnetocaloric properties of rare earth intermetallic compound Gd3Co4Ge13.

Author

Morozkin, A. V., Garshev, A. V., Yapaskurt, V. O., Quezado, S., Malik, S. K., and Nirmala, R.

Subjects
MAGNETIC properties, RARE earth metal compounds, MAGNETIC field measurements, MAGNETIC fields, MAGNETIC moments, YTTERBIUM
Abstract

Magnetic and magnetocaloric properties of polycrystalline Gd3Co4Ge13 (Cubic, Yb3Rh4Sn13-type, Space group Pm-3n, No. 223, cP40) have been studied by carrying out dc magnetization measurements in applied magnetic fields up to 140 kOe. The compound Gd3Co4Ge13 orders antiferromagnetically at 9 K (TN). The antiferromagnetism appears to be weak and with increasing applied magnetic fields, ferromagnetic interactions become dominant. This field-induced antiferromagnetic to ferromagnetic state that is marked as a change from inverse to normal magnetocaloric effect in the isothermal magnetic entropy change vs temperature plot around TN. At 2 K, the magnetization shows a tendency toward saturation in applied magnetic field and a magnetic moment of 5.3 µB per Gd3+ is obtained in 140 kOe field. [ABSTRACT FROM AUTHOR]

Published
2024
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44. Tailoring the magnetocaloric, magnetic and thermal properties of Dy6(Fe,Mn)X2 intermetallics (X==Sb, Te, Bi)

Author

Física aplicada I, Fisika aplikatua I, Herrero Hernández, Aritz, Oleaga Páramo, Alberto, Rodríguez Aseguinolaza, Iván, García Adeva, Angel Javier, Apiñaniz Fernández de Larrinoa, Estibaliz, Garshev, A. V., Yapaskurt, V. O., Morozkin, A. V., Física aplicada I, Fisika aplikatua I, Herrero Hernández, Aritz, Oleaga Páramo, Alberto, Rodríguez Aseguinolaza, Iván, García Adeva, Angel Javier, Apiñaniz Fernández de Larrinoa, Estibaliz, Garshev, A. V., Yapaskurt, V. O., and Morozkin, A. V.

Abstract

[EN] The structural, magnetic, magnetocaloric (MCE) and thermal properties of seven Fe2P-type Dy6(Fe,Mn)X2 (X=Sb, Bi, Te) intermetallics (space group P 6 over line 2 m, N 189, hP9) have been experimentally studied. They present a paramagnetic to ferromagnetic transition (in the range 129-370 K), followed, as temperature decreases, by a spin-reorientation one (from 52 to 170 K) and a ground magnetic state at 2 K with anti-ferromagnetic components. This state turns into a ferromagnetic state when a magnetic field is applied. The critical exponents beta,gamma,delta related to the PM-FM transition point to long range order interactions but in most compounds their values severely deviate from the Mean Field class, presenting an unconventional critical behavior, probably due to magnetocrystalline anisotropies. This magnetic complexity has the consequence that in every intermetallic three MCE effects arise: Two direct magnetocaloric effects (DMCE) with a table-like effect in between (from 40 K to more than 400 K), with moderate values of the magnetic entropy maxima (up to 6.9 J/kgK for 140 Delta H = 5 T, with the tableau in-between being around 4 J/kgK, for Dy6FeSb2 and Dy6FeSbTe). The calculation of the Thermal Average Entropy Change allows to place the properties of two compounds (Dy6FeSb2 and Dy6FeSbTe) close to other rare earth based high entropy alloys described in literature. The seven compounds present a relevant third MCE, inverse, below 25 K, with a value as high as 17.8 J/kgK (140 Delta H = 5 T) for Dy6FeSbTe. The maximum of the magnetic entropy change at the Curie tem-perature has been shown to scale with the critical exponents found and universal curves have been built. Finally, the thermal diffusivities in the range of the DMCE have been measured, with the result that they present good values (between 1 and 3 mm2/s) to be used in real magnetocaloric refrigeration systems.

Published
2022

45. Selecting optimal R6TX2 intermetallics (R = Gd, Tb, Dy; T = Mn, Fe, Co, Ni; X = Sb, Te) for magnetic refrigeration.

Author

Herrero, A., Aseguinolaza, I. R., Oleaga, A., Garcia-Adeva, A. J., Apiñaniz, E., Garshev, A. V., Yapaskurt, V. O., and Morozkin, A. V.

Subjects
MAGNETIC entropy, MAGNETIC cooling, RARE earth metals, MAGNETIC transitions, SPECIFIC heat capacity, MAGNETOCALORIC effects, TERBIUM, THERMAL diffusivity
Abstract

A complete experimental study of the physical properties playing a relevant role in the magnetic refrigeration application (structural, magnetic, magnetocaloric and thermal) has been performed over nine selected Fe2P-type R6TX2 (R = Gd, Tb, Dy; T = Mn, Fe, Co, Ni; X = Sb, Te) intermetallic compounds, to work close to room temperature. Two magnetic phase transitions are observed for these materials: a paramagnetic to ferromagnetic transition in the range of 182–282 K and a spin reorientation transition in the range of 26–76 K. As a consequence, two peaks related to a direct magnetocaloric effect (DMCE) appear with the magnetic entropy change, generating a wide table-like plateau region in between both peaks, which is required to improve the efficiency of refrigerators following an Ericsson cycle. The highest magnetic entropy peak value for μ0ΔH = 5 T is found for Tb2Dy4FeSb2, with 7.72 J kg−1 K−1 around 182 K. For the same applied field the other compounds show moderate values around room temperature (2.88–4.53 J kg−1 K−1). However, the superposition of the two peaks results in huge refrigerant capacity values, up to RCFWHM(5 T) = 1103.04 J kg−1 in the case of Tb2Dy4FeSb2. The thermal diffusivity, thermal effusivity, thermal conductivity and specific heat capacity have been measured at room temperature, and the temperature dependence of the former has been obtained around the relevant magnetic phase transition region, with values in the range of 1.3–2.3 mm2 s−1, which are good for magnetic refrigerators at high working frequencies. The study is completed with a rigorous critical behavior analysis of the second order PM–FM transition. The critical exponent γ points to long range order interactions, in general, while β values are in the range of 0.59–0.90, indicating a deviation from theoretical models as a reflection of the magnetic complexity in these compounds. The critical exponents have been used to confirm the scaling relations of magnetocaloric properties, and the scaling of refrigerant capacity (RC) values in materials exhibiting two magnetic phase transitions is addressed, concluding that for a correct scaling of RC the magnetic entropy change peak must be considered symmetric. The role of each atom in the properties of the compounds is discussed. [ABSTRACT FROM AUTHOR]

Published
2023
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