The magnetic entropy change of tetragonal and orthorhombic NiMnGa fine particles made by spark erosion was investigated in this paper. It was found that the structure and crystalline phase transformation temperatures can be strongly affected by the compositions of the particles, while Curie temperature is less sensitive to the compositions. Due to the possible distribution of the particle size and compositions in these particles, the magnetic entropy changes observed are much broader and smaller than those of bulk NiMnGa alloys. The maximum absolute value of entropy change ΔS=2 J Kg-1 K-1 was observed for tetragonal structure NiMnGa particles at 95 °C in a field of 2 T.
ASJC Scopus subject areas
- Physics and Astronomy(all)