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

• The minimum anisotropy is realized around x=0.15.
• EMD at RT is detected rotating from <100> to <111> axis with increasing Tb content.
• A large saturation magnetostriction (λS~445 ppm) is obtained for x=0.15.

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~445 ppm, λa~510 ppm/3 kOe) 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~300 ppm) and the Tb0.15Ho0.85Fe2 (λS~325 ppm), due to the 20 at% 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.