Influence of Pr-doping on the magnetic properties and magnetocaloric effect of Ni50−xPrxMn37Sn13 alloys

We have studied the magnetic and magnetocaloric (MC) properties of Ni50−xPrxMn37Sn13 (x = 0, 1, 3, and 5) alloy ingots fabricated by arc-melting. Experimental results revealed a coexistence of the conventional and inverse MC effects in the samples with x = 0, 1, and 3. There is a gradual decrease of the magnetization and magnetic-entropy change (ΔSm) when Pr-doping content increases. However, the Curie temperature of the austenitic phase (TCA) around room temperature was not changed very much. Particularly, doping a small amount of Pr with x = 1 enhances remarkably the linewidth of the peaks in its ΔSm(T) curves. This increases the relative cooling power (RCP) of Ni50−xPrxMn37Sn13 alloys when they are used as coolants in refrigeration devices. For example, under an applied field of H = 50 kOe, the RCP increases from 150 for x = 0 to ∼200 J/kg for x = 1. Higher Pr contents reduce quickly the MC effect because of the formation of nonmagnetic secondary phases.