Structure and magnetostriction of Nd0.67Tb0.33(Co1 xFex)2compounds

The crystal structure, Curie temperature and magnetostriction of compounds with the formula Nd 0.67 Tb 0.33 (Co 1− x Fe x ) 2 were investigated by x-ray powder diffraction and magnetic measurements. It is revealed that the substitution of Fe for Co destabilizes the cubic Laves phase Nd 0.67 Tb 0.33 (Co,Fe) 2 . The maximum substitution of Fe for Co is about 0.57. The lattice constant of the Nd 0.67 Tb 0.33 (Co,Fe) 2 phase increases with x increasing from x = 0.0 to 0.6, then remains almost unchanged from x = 0.6 to 0.9. The Curie temperature exhibits a variation similar to that of the lattice constant with the Fe concentration. A spin reorientation is observed, which can be understood on the basis of the two-sublattice model. The spontaneous magnetostriction constant λ 111 shows a maximum value of 1.7 × 10 −3 at x = 0.4. The temperature dependence of λ 111 for Nd 0.67 Tb 0.33 (Co 0.6 Fe 0.4 ) 2 exhibits an abrupt jump at 165 K, which corresponds to the temperature of the spin reorientation.