Electrocaloric Ni2MnGa is of interest for solid state refrigeration applications, as well as a high temperature thermal shape memory alloy. Here, polycrystalline Ni54Mn25Ga21 is examined using in situ synchrotron X-ray diffraction. The initial martensite (Mf) and austenite (Af) finish temperatures were found to be 232 ° C and 298 ° C respectively. Mf was observed to decline by 8 ° C/cycle and Af increased by 1 ° C/cycle. Both below and surprisingly, above the Curie temperature, the application of an e.m.f. was found to affect the lattice parameters measured. A change in the thermal expansion of the two phases was found around the Curie temperature.
- ferromagnetic shape memory alloy
- intermetallic compounds
- synchrotron radiation
- thermal expansion