Giant low-field magnetostriction of epoxy/TbxDy1−x(Fe0.8Co0.2)2 composites (0.20 ≤ x ≤ 0.40)

Abstract

Spin configuration, magnetocrystalline anisotropy compensation, and magnetostriction of TbxDy1−x(Fe0.8Co0.2)2 (0.20 ≤ x ≤ 0.40) compounds have been investigated. Experimental evidence for the anisotropy compensation has been observed directly by performing x-ray diffraction on magnetic-field aligned powders and by evaluating the Mössbauer spectra. The easy magnetization direction (EMD) at room temperature rotates from the ⟨100⟩ (x ≤ 0.27) to the ⟨111⟩ axis (x ≥ 0.32), subjected to the anisotropy compensation between Tb3+ and Dy3+ ions. The strong grain-⟨111⟩-oriented pseudo-1–3 epoxy/composite has been fabricated by curing under a moderate magnetic field. A giant low-field magnetostriction, longitudinal λ|| and linear anisotropic λa (=λ|| − λ⊥) up to 550 and 760 ppm at 3 kOe, respectively, is obtained for Tb0.32Dy0.68(Fe0.8Co0.2)2 composite, which can be attributed to anisotropy compensation, a large magnetostriction coefficients λ111, EMD lying along ⟨111⟩ direction, the strong ⟨111⟩-textured orientation, and the chain structure. The good magnetoelastic properties, besides only containing 27 vol. % alloy particles in the insulating epoxy, make it a promising candidate for magnetostriction applications.