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Magnetocaloric manganites: Progress and challenges
Phan, Manh-Huong,Yu, Seong-Cho WILEY-VCH Verlag 2007 Physica status solidi. PSS. A, Applications and ma Vol.204 No.12
<P>Magnetic refrigeration based on the magnetocaloric effect (MCE) becomes a topic of internationally current interest. This enabling technology provides several advantages (e.g. high energy efficiency, small volume, non-pollution) over a conventional gas compression technique. It depends heavily upon the magnitude of MCE of magnetic substances that are used as working refrigerants. Therefore, current research is focused on a search for new materials that are low cost and exhibit small magnetic field-induced large MCEs. This paper aims to review the recent developments of a new class of magnetocaloric material, namely, ferromagnetic manganites (R<SUB>1-x</SUB>M<SUB>x</SUB>MnO<SUB>3</SUB>, where R = La, Nd, Pr and M = Ca, Sr, Ba, etc.). The good magnetocaloric properties of ferromagnetic manganites in addition to their flexibility and cost-effectives make them very promising for active magnetic refrigeration (AMR) applications in the temperature range of 30–375 K. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)</P>
Large magnetic entropy change above 300 K in manganites
Manh-Huong Phan,유성초,J.S Kim,박승훈,The-Long Phan 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.45 No.3
An investigation into the magneto-caloric eect in several compounds: La0:65Sr0:35MnO3, La0:6Sr0:2Ca0:2MnO3, La0:6Sr0:2Ba0:2MnO3, La0:7Ba0:3MnO3 and La0:7Ba0:24Ca0:06MnO3 was carried out. Among the compositions investigated, La0:6Sr0:2Ba0:2MnO3 has the highest value, at 2.26 J/kg/K, for j 4Smax M j at TC = 354 K, with 10 kOe applied eld. The adiabatic temperature change, 4Tad, of this sample is estimated to be 1:1 K and 4:95 K with elds of 10 kOe and 50 kOe, respectively. Since a signicant change in magnetic entropy of the present compounds has been found to occur around 300 K, these materials are attractive candidates for room-temperature magnetic refrigeration applications. The large magnetic entropy change in the manganese perovskites must have originated from the abrupt reduction of magnetization which is associated with the ferromagnetic to paramagnetic transition at the Curie temperature.