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

► Same content of monovalent elements doped in the manganites. ► The transition temperatures are at room temperature. ► Large magnetocaloric effect under low magnetic field change of 1.5 T.