Effect of partial Gd substitution on the magnetic and magnetocaloric properties in Dy-Ho-Gd-Co multicomponent compounds

The magnetic and magnetocaloric properties of polycrystalline (Dy0.9Ho0.1)(1-x)GdxCo2 (0.0x0.15) solid solutions were investigated experimentally using magnetic measurements; the Landau theory was also applied to clarify peculiarities of the 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 increased from 0.7186 for x=0.0 to 0.7194nm for x=0.15 and the Curie temperature T-C increases from 130 to 183K as the Gd content increases to x=0.15. The isothermal entropy change S-mag was calculated according to magnetic measurements using the thermodynamic Maxwell's relation. A decrease in entropy change with the increase of Gd content has been observed. Under an external field change of from 0 to 3T, the maximum entropy change decreased from 8.1 for x=0.0 to 4.3Jkg(-1)K(-1) for x=0.15. The effect of increasing the Gd amount in the (Dy0.9Ho0.1)(1-x)GdxCo2 solid solutions on their magnetic and magnetocaloric properties is discussed. (C) 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim