Magnetocaloric Effect of Fe(Rh_1−xPd_x) Alloys

Abstract

Magnetocaloric effects of Fe₄₉(Rh_1−xPd_x)₅₁ alloys with x=0.0, 0.01, 0.03, 0.06, 0.07, 0.08, and 0.09, were investigated using resistivity, magnetization, specific heat, and direct measurement of the adiabatic temperature change ΔT. Magnetization measurements yielded experimental values of the isothermal magnetic-entropy change ΔS for all the samples. The critical temperature of the anitiferromagnetic-ferromagnetic transition was found to depend largely on the substitution concentrations of Pd. A broad peak in ΔS, up to 1.7 J·mol⁻¹ K⁻¹ and some 90 K broad around room temperature, was observed with a field change of ΔB=0 to 7 T for Fe₄₉(Rh_0.97Pd_0.03)₅₁. The specific heat data of Fe₄₉(Rh_0.97Pd_0.03)₅₁ made it possible to estimate the ΔT values for various external fields. This estimated value of ΔT compares well with the value measured directly using a thermocouple.