Optimization on magnetic anisotropy and magnetostriction in TbxHo0.8−xPr0.2(Fe0.8Co0.2)1.93 compounds

Abstract

The structure, magnetocrystalline anisotropy compensation, magnetic properties, and magnetostriction of TbxHo0.8–xPr0.2(Fe0.8Co0.2)1.93 (0≤x≤0.30) polycrystalline alloys have been investigated. X-ray diffraction (XRD) analysis shows that all the alloys stabilize in the single Laves phase with a MgCu2-type cubic structure. The lattice parameter, Curie temperature and saturation magnetization monotonically increase with increasing Tb content. The easy magnetization direction (EMD) at room temperature is detected rotating from the <100> axis (x≤0.10) to the <111> axis (x≥0.15), accompanied by a rhombohedral distortion with large spontaneous magnetostriction coefficients λ111. The analysis of XRD, EMD and magnetostriction shows that TbxHo0.8–xPr0.2(Fe0.8Co0.2)1.93 is an anisotropy compensation system, and the critical compensation point is realized around x=0.15, which shifts to the Tb-poor side compared with the Pr-free counterpart. An optimized effect on magnetostriction especially at a relatively low field (λS~445ppm, λa~510ppm/3kOe) was obtained in Tb0.15Ho0.65Pr0.2(Fe0.8Co0.2)1.93 compound, which is much larger than that of the Pr-free counterpart Tb0.15Ho0.85(Fe0.8Co0.2)1.93 (λS~300ppm) and the Tb0.15Ho0.85Fe2 (λS~325ppm), due to the 20at% Pr introduction. Low content of heavy rare earth Tb, low anisotropy, high saturation magnetostriction and large low-field magnetostriction are obtained in Tb0.15Ho0.65Pr0.2(Fe0.8Co0.2)1.93 compound, which may make it a promising magnetostrictive material.