Effect of partial Ho-substitution on the magnetic and magnetocaloric properties of polycrystalline DyCo2-based solid solutions

Structural, magnetic and magnetocaloric properties and heat capacity of polycrystalline Dy1−xHoxCo2 (0.1 ⩽ x ⩽ 0.5) solid solutions were investigated experimentally using by X-ray diffraction, magnetic and heat capacity measurements; the Landau theory was applied also to clarify peculiarities of magnetic phase transition in the compounds.X-ray diffraction patterns taken at room temperature exhibit the existence of the C15 cubic Laves phase structure for all samples under study. The lattice parameter decreased from 0.7186 for x = 0.1–0.7179 nm for x = 0.5 and the Curie temperature TC decreases from 130 to 109 K as the Ho content increases to x = 0.5. The isothermal entropy change −ΔSmag was calculated according to magnetic measurements using thermodynamic Maxwell’s relation. A large entropy change has been observed for all Ho concentrations. Under an external field change from 0 to 3 T, the maximum entropy change fluctuates within 9 J/kg K. The maximum ΔTad value varies within 3 and 2 K for a magnetic field change of 2 and 1 T, respectively. The effect of increasing Ho amount in the Dy1−xHoxCo2 solid solutions on their magnetic and magnetocaloric properties is discussed.

► Polycrystalline DyCo2 based solid solutions.
► The Landau theory was applied.
► A large entropy change has been observed.
► The materials highly attractive for magnetic cooling applications.