Power Losses in LaFexCoySi1.1 Intermetallics near the Magnetic Phase Transition
R. Gozdura, M. Lebioda b and Ł. Bernacki a
aŁódź University of Technology, Department of Semiconductor and Optoelectronics Devices, B. Stefanowskiego 18/22, 90-924 Łódź, Poland
bŁódź University of Technology, Institute of Electrical Engineering Systems, B. Stefanowskiego 18/22, 90-924 Łódź, Poland
Received: February 2, 2015
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The paper presents magnetic parameters of LaFexCoySi1.1 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 LaFe10.8Co1.1Si1.1 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 TΔSmax and Tc 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 TΔSmax 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.

DOI: 10.12693/APhysPolA.128.98
PACS numbers: 75.30.Sg, 75.30.Kz, 75.50.Bb