PROJECT TITLE :

Large Magnetic Entropy Change in La0.6Ce0.4Fe11.5Si1.5 Alloy Exhibiting First- and Second-Order Phase Transitions

ABSTRACT:

A polycrystalline alloy ingot of La0.6Ce0.4Fe11.5Si1.5 was ready by an arc-melting methodology. Magnetic measurements of magnetization M as a function of field H and temperature T show a ferromagnetic-paramagnetic section transition at a Curie temperature TC = a hundred and seventy K. Interestingly, curves of H/M versus M2 have a positive slope at low field (H ≤ 10 kOe), which corresponds to a second-order part transition (SOPT), however a negative slope at high field (H > 10 kOe), which corresponds to a 1st-order phase transition (FOPT). The magnetic entropy modification ΔSm(T) underneath totally different ranges of field amendment ΔH, calculated from M(H) isotherms, contains a most IΔSmaxI around TC that will increase in magnitude with increasing ΔH. Refrigerant capacity (RC), indicative of magnetic cooling efficiency, conjointly increases with increasing ΔH. Curves of ΔSm(T)/ΔSmax versus θ = (T - TC)/(Tr - TC), where Tr is the reference temperature, collapse into a universal curve when ΔH ≤ ten kOe. In contrast, curves of ΔSm(T)/ΔSmax versus θ do not scale back to a universal curve when ΔH > ten kOe. These counsel a coexistence of FOPT and SOPT properties in the alloy.