Contribution of entropy changes to the inverse magnetocaloric effect for Ni46.7Co5Mn33In15.3 Heusler alloy

In this paper, the changes of volume fractions between austenitic and martensitic phase have been carefully deduced through magnetization data for polycrystalline Ni46.7Co5Mn33In15.3 alloy during reverse martensitic transformation at different magnetic fields. On this basis, the contributions of the lattice and the spin components to the total entropy changes could be effectively separated by using the Clausius-Clapeyron equation and the Debye theory calculations, It is concluded that the lattice contribution works against the magnetic contribution to the inverse magnetocaloric effect (MCE) in this alloy. Further analysis indicates that the effective inverse MCE comes from field-induced variation of the crystal structure. On the contrary, the change of the magnetic moment alignment in this process yields negative contribution, leading to a reduction of the total inverse MCE by about 33%. (C) 2014 Elsevier Ltd. All rights reserved