Spontaneous magnetostriction of Laves phase Nd1−xTbxCo2 compounds

The crystal structure and magnetostriction of Nd1-xTbxCo2 compounds were investigated by temperature dependent X-ray powder diffraction. It is revealed that all samples retain the cubic Laves phase C15 structure above their Curie temperature T-C. A rhombohedral distortion at low temperature is revealed for the samples from x = 0.4 to 1.0 and the temperature dependence of the anisotropic magnetostriction constant lambda(111) is calculated. The anisotropy constant K-1 exhibits a minimum value between x = 0.3 and 0.4. The calculated spontaneous volume magnetostriction exhibits an anomaly between x = 0.3 and 0.4, which is likely to be associated with an abrupt change of the Co moment in this concentration region. (C) 2003 Elsevier B.V. All rights reserved.