Magnetocaloric effect of Sr-substituted BaFeO3 in the liquid nitrogen and natural gas temperature regions

We have investigated the magnetocaloric effect (MCE) of Ba1-xSrxFe4+O3 (x≤0.2), a series of cubic perovskites showing a field-induced transition from helical antiferromagnetism to ferromagnetism. The maximum magnetic entropy change (-ΔSmax) at 50 kOe varies from ∼5.8 J kg-1K-1 (x=0) to ∼4.9 J kg-1K-1 (x=0.2), while the refrigerant capacity remains almost the same at ∼165 J kg-1. Interestingly, the temperature of -ΔSmax decreases from ∼116 K to ∼77 K with increasing x, providing this series of rare-earth-free oxides with potential as a magnetic refrigerant for the liquefaction of nitrogen and natural gas