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MA: Fachverband Magnetismus

MA 13: Magnetic Materials II

MA 13.5: Talk

Monday, March 14, 2011, 18:00–18:15, HSZ 401

Magnetocaloric effect and thermal stability of hydrogenated melt spun La(Fe,Si)₁₃-compounds — •Maria Krautz, Konstantin Skokov, James D. Moore, Jian Liu, Ludwig Schultz, and Oliver Gutfleisch — IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, D-01171 Dresden

3d-metal based alloys with a NaZn₁₃-structure are of high interest for magnetic refrigeration as they show a large magnetocaloric effect by undergoing a first-order phase transition. Since only LaCo₁₃ is stable as a binary, the LaFe₁₃-phase must be stabilised by additional elements such as Al or Si. In pseudobinary La(Fe,Si)₁₃ alloys the magnetic transition temperature can be tuned by inserting interstitial hydrogen. In this work, almost single phase La(Fe,Si)₁₃ alloys produced by melt spinning and subsequent short time annealing are hydrogenated at elevated temperatures. In view of application, the hydrogen content was adjusted to cover a range of Curie temperatures. A systematic study of different particle sizes on the hydrogenation was carried out. The influence of hydrogen on the magnetocaloric properties was studied by direct adiabatic temperature change measurements and indirect methods to determine the magnetic entropy change. Finally, the stability of the hydrogenated samples is assessed.