Effect of Fe substitution on magnetic and magnetocaloric effect in Gd(Co_1-xFe_x)₂B₂ compounds

Polycrystalline samples of Gd(Co_1-xFe _x)₂B₂ (x 0, 0.1, 0.2, and 0.4) compounds have been prepared and their magnetic properties and magnetocaloric effect (MCE) have been studied by the magnetization and heat capacity measurements. As the Fe content x increases up to 0.4, the magnetic ordering temperature T_M increases gradually from 19 to 32 K, the maximum values of magnetic entropy change -ΔS_M^max decreases gradually from 17.1 to 12.1 J/kg K without obvious hysteresis around its own ΔT_M for a field change of 5 T, and the corresponding adiabatic temperature change T _ad^max also decreases gradually from 15.4 to 8 K. The reduction in the MCE of Gd(Co_1-xFe_x) ₂B₂ system could be explained by the fact that the increase in the Fe content transforms the magnetic transition type from a first order type to a second order type. The values of relative cooling power (RCP) are 462, 434, 499, and 415 J/kg for x 0, 0.1, 0.2, and 0.4 in Gd(Co _1-xFe_x)₂B₂, respectively. The magnetic transition and Fe substitution effect on MCE as well as its potential application in Gd(Co_1-xFe_x) ₂B₂ system were discussed.