A New Simplified Method to Evaluate the Property Parameters of Polycrystalline Magnetic Caloric Materials

The magnetic entropy change and other relevant property parameters were calculated by the simplified method proposed by Mahmoud A. Hamad (referred to as the MAH method) and the conventional method, respectively, using the experimental data of magnetization versus magnetic field and temperature of polycrystalline La 0.6 Sr 0.2 Ba 0.2 MnO 3 . By comparing and analyzing the different results from the two methods, the intrinsic problems involved with the MAH method were disclosed, and a new simplified method to precisely evaluate the magnetic caloric properties of polycrystalline magnetic materials has been proposed, which is based on the fact that the magnetization of a polycrystalline magnetic material varies as a function of both applied magnetic field and temperature and, moreover, the magnetic field dependence of ( ∂ M / ∂ T ) can be approximately described by a two-segmented linear function over the whole field range. Compared to the conventional method, this new simplified method needs much fewer experimental data but provides good evaluations of property parameters for a polycrystalline magnetic caloric material.