Magnetic behaviour and experimental study of the magnetocaloric effect in the pseudobinary Laves phase Er1−xDyxCo2
Résumé
We have investigated the crystal structure, the bulk magnetization characteristics and the magnetocaloric properties of Er1−xDyxCo2 compounds. X-ray diffraction (XRD) analyses confirm that all these Lavesphase type compounds crystallize in the cubic MgCu2-type structure. First, the magnetization behaviour and the magnetic transition are analyzed in terms of Landau theory. Then, a direct correlation was pointed out between the character of the magnetic transition and the behaviour of the cell parameter versus x. Substitution of Dy to Er enhances markedly the Curie temperature TC from 35 to 142 K, while ΔS the corresponding change of isothermal entropy decreases significantly. The refrigerant capacity of the Er1−xDyxCo2 compounds is discussed and our experimental data are compared with the corresponding theoretical results reported in the literature [de Oliveira, von Ranke, J. Magn. Magn. Mater. 264 (2003) 55].