Investigation of magnetocaloric effect in La 0.45Pr 0.25Ca 0.3MnO 3 by magnetic, differential scanning calorimetry and thermal analysis

Abstract

We investigated magnetocaloric effect in La 0.45Pr 0.25Ca 0.3MnO 3 by direct methods (changes in temperature and latent heat) and indirect method (magnetization isotherms). This compound undergoes a first-order paramagnetic to ferromagnetic transition with T C=200 K upon cooling. The paramagnetic phase becomes unstable and it transforms into a ferromagnetic phase under the application of magnetic field, which results in a field-induced metamagnetic transition (FIMMT). The FIMMT is accompanied by release of latent heat and temperature of the sample as evidenced from differential scanning calorimetry and thermal analysis experiments. A large magnetic entropy change of ΔS m=-7.2 J kg -1 K -1 at T=212.5 K and refrigeration capacity of 228 J kg -1 are found for a field change of ΔH=5 T. It is suggested that destruction of magnetic polarons and growth of ferromagnetic phase accompanied by a lattice volume change with increasing magnetic field is responsible for the large magnetocaloric effect in this compound. © 2012 Elsevier B.V. All rights reserved.