Magnetocaloric effect and the change from first- to second-order magnetic phase transition in Pr0.7CaxSr0.3-xMnO3 polycrystalline compounds

The work presents the magnetocaloric effect and critical behavior of monoclinic polycrystalline Pr0.7CaxSr0.3-xMnO3 prepared by solid state reaction. The ferromagnetic-paramagnetic phase transition temperature decreases from 267, 202, 138 to 126 K with increasing doping concentration from x=0 to 0.3. The maximum values of entropy change appear near the transition phase points and were found to be 6.4, 7.2, 3.9 and 4.0 J.kg-1.K-1 with 5 Tesla of field change for x=0-0.3, respectively. However, the shift to the higher temperature side with the increasing field change was observed clearly in sample x=0.1. Besides, the considering magnetic phase transition of samples based on Banerjee’s criterion showed a first-order phase transition in Pr0.7Ca0.1Sr0.2MnO3 (x=0.1) while samples with x=0, x=0.2 and 0.3 exhibited a second-order phase transition.