Structure and magnetic properties of magnetostrictive compounds Tb0.36Dy0.64(Fe0.85Co0.15)2−xBx (0⩽x⩽0.15)

Crystal structure and magnetic properties of magnetostrictive compounds Tb0.36Dy0.64(Fe0.85Co0.15)2−xBx (0⩽x⩽0.15) have been investigated at room temperature. The matrix of these compounds keeps a cubic MgCu2-type structure. Lattice parameter a of the Laves phase decreases to reach a minimum at x=0.10, then increases with increasing boron content. Through analyzing the Mössbauer spectra, the easy magnetization direction (EMD) for all samples is confirmed to lie along 〈111〉 direction at room temperature, suggesting the presence of the giant magnetostriction. The mean hyperfine field Hhf and the deduced iron moment μFe increase with increasing boron content, resulting in the enhancement of both Curie temperature TC and spin reorientation temperature Tr. Although the addition of B enlarges the magnetocrystalline anisotropy constant K1, the composition dependence of the ratio λ/K1 for Tb0.36Dy0.64(Fe0.85Co0.15)2−xBx, however, reaches a maximum value at x=0. 05 under high magnetic fields.