Magnetocaloric effect in compounds and composite based on manganese arsenide

Pankratov, N.Y.; Mitsiuk, V.I.; Smarzhevskaya, A.I.; Govor, G.A.; Nikitin, S.A.

Авторы: Pankratov N.Yu, Mitsiuk V.I., Smarzhevskaya A.I., Govor G.A., Nikitin S.A.
Сборник: Abstracts of International Conference "Functional Materials" ICFM‘2013 September 29 - October 5, 2013. Ukraine, Crimea, Yalta, Haspra
Тезисы
Год издания: 2013
Место издания: Simferopol, DIP Simferopol, Ukraine
Первая страница: 89
Последняя страница: 89
Аннотация: The magnetocaloric effect is important because of its potential application in the industrial refrigerator. It is characterized by the adiabatic temperature variation and the isothermal entropy change and reaches maximum at temperature of magnetic phase transition. The greatest interest is attracted by materials with giant MCE. The aim of this work was to investigate the magnetization and MCE of some compounds and polymeric composites based on MnAs, possessing by magnetic phase transition near room temperature and finding the dependence of MCE and unstable magnetic condition to be produced by thermal and magnetic history of sample. The single crystal of MnAs, MnAs(Sb) MnAs(P) were growned by the Stockbarger-Bridgman method and were characterized by X-ray diffraction at room temperature. There were obtained both textured by magnetic field and isotropic samples fixed by hydrostatic pressure up to 20 kbar. It was found that MnAs demonstrates a strong temperature and field hysteresis of magnetic properties in magnetic field less than 50 kOe. Our results show that the maximum value of MCE is ΔT = 0.28 K on heating (at 308 K) and ΔT = 0.88 K on cooling (at T = 306 K) for MnAs. The maximum change of magnetic entropy is about 40 J/kg·K for 140 kOe. It was shown that both ferro- and paramagnetic metastable phase coexist in MnAs in the region of phase transition, and so the giant MCE is caused by magnetic phase transition from paramagnetic to ferromagnetic state. Since the relation of ferro- and paramagnetic phases are different on heating and cooling, so the magnitudes of MCE at heating and cooling are different. It was found that the composite material based on microcrystalline MnAs and polymeric matrix fixing under pressure 10 kbar which show quasi-inverse MCE behavior at heating and cooling. The maximum of MCE is ΔT ~ 1,3 K (at 309 K).
Добавил в систему: Панкратов Николай Юрьевич

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