Experimental study of the magnetocaloric effect in Dy1−xErxCo2 solid solutions doped with Gd

Magnetic and magnetocaloric properties of polycrystalline (Dy0.9Er0.1)1−xGdxCo2 (0.0 ⩽ x ⩽ 0.25) solid solutions were investigated experimentally using magnetic measurements. The magnetization behavior and magnetic transition are analyzed in terms of Landau theory. Powder X-ray diffraction analysis performed at room temperature showed that all (Dy0.9Er0.1)1−xGdxCo2 (0.0 ⩽ x ⩽ 0.25) solid solutions are C15 cubic Laves phase with the MgCu2-type structure. The lattice parameter increases from 0.7187 for Dy0.9Er0.1Co2 to 0.7204 nm for (Dy0.9Er0.1)0.75Gd0.25Co2. In this case, the Curie temperature increases from 128 K to 215 K for. At higher temperatures, all solid solutions are Curie-Weiss paramagnets. The isothermal entropy change −ΔSmag was calculated using magnetic measurements data and thermodynamic Maxwell's relation. A decrease in the entropy change has been observed with increasing Gd content. Under an external field change of from 0 to 3 T, the maximum entropy change for these compounds decreases from 8.5 at x = 0.0 to 3.1 J/kg K at x = 0.25. The refrigerant capacity of the (Dy0.9Er0.1)1−xGdxCo2 solid solutions (with 0.0 ⩽ x ⩽ 0.25) is presented. The effect of increasing Gd content in the (Dy0.9Er0.1)1−xGdxCo2 solid solutions on their magnetic and magnetocaloric properties is discussed.