Effect of monovalent metal substitution on the magnetocaloric effect of perovskite manganites Pr0.5Sr0.3M0.2MnO3 (M=Na,Li, K and Ag)

The influence of monovalent doping on the magnetocaloric effect (MCE) and refrigerant capacity or relative cooling power (RCP) of Pr_0.5Sr_0.3M_0.2MnO₃ (M=Na, Li, K and Ag) materials has been investigated. A large magnetocaloric effect was inferred over a wide range of temperature around the second order paramagnetic–ferromagnetic transition. The maximum magnetic entropy changes (ΔS_M) reached 1.8, 2.2, 1.6 and 2.1 J/kg K and the relative cooling power (RCP) approached 58.9, 59.3, 69.6 and 54.6 J/kg for Na, Li, K and Ag doped materials in the magnetic change of 15 kOe, respectively. According to the results determined by the Maxwell relation, the magnetic entropy change fits well with the Landau theory of phase transition above T_C for Pr_0.5Sr_0.3Li_0.2MnO₃. The large magnetic entropy change induced by low magnetic field suggested that these materials are beneficial for practical applications.