Structure, magnetic properties, and magnetostriction of Sm0.88Dy0.12(Fe1−xMx)2 (M=Mn, Al) (0⩽x⩽0.2)

Abstract

The structure, magnetic properties, and magnetostriction of arc-melted polycrystalline Sm0.88Dy0.12(Fe1−xMx)2 (M=Mn, Al, 0⩽x⩽0.2) alloys were investigated by microscopy, x-ray diffraction, A.C. initial susceptibility, vibrating sample magnetometry, and standard strain gauge techniques. It was found that the matrix consists almost entirely of the MgCu2-type cubic Laves phase, with a small amount of rare-earth rich phase. The lattice parameter increases approximately linearly with increasing x from 0.740 to 0.750 nm for M=Al. For M=Mn the lattice parameter increases by 0.002 8 nm over the same increase in x. The Curie temperature decreases with increasing x from 670 to 410 and 550 K for M=Al and Mn, respectively. The spontaneous magnetostriction, λ111, and polycrystalline magnetostriction, λs, both decrease with increasing Al or Mn substitution for Fe from their initial values of −1452 and −1010 ppm, respectively. Premature disappearance of the splitting of the (440) line and changes in the shape of the magnetostriction curves suggest the substitution of Mn for Fe may produce a change in the anisotropy. No such effects were observed for M=Al. The saturation magnetization, MS, decreases approximately linearly with increasing substitution of Al or Mn. The changes in the magnetization and magnetostriction can be understood on the basis of a decreasing 3d sublattice moment.