Crystal structure and magnetic properties of Gd3(Fe1-x-yCoyTix)29 compounds

A series of Gd3 (Fe1-x-y CoyTix)29 (x = 0.011-0.034, y 0-0.393) samples have been prepared. Single-phase samples assigned as 3:29 compounds with the monoclinic lattice are obtained in the following composition regions: x = 0.011, 0 ≤ y ≤ 0.307; x = 0.022, 0 ≤ y ≤ 0.313; and x = 0.034, 0 ≤ y ≤ 0.393. The solid-solution limit of cobalt in Gd3 (Fe1-x-yCoyTix)29 increases with the Ti content. The cell parameters a , b and c show anisotropic decreases with the Co content, i.e. a and b decrease significantly and c decreases slightly in the composition range investigated. The Curie temperature is increased by the substitution of Co for Fe in Gd3 (Fe1-x-yCoyTix)29. The saturation magnetization first increases and then decreases with the Co content. The dependence of the intrinsic magnetic properties of Gd3 (Fe1-x-y CoyTix)29 on the Co and Ti contents is presented. The compounds exhibit an easy-magnetization direction on the a-b plane corresponding to the CaCu5-type structure at room temperature. The anisotropy field Ha of Gd3 (Fe1-x-yCoyTix)29 is decreased and the magnetocrystalline anisotropy constant K1 is increased by the substitution of Co for Fe. No spin reorientation is observed in the alternating-current susceptibility measurement between 77 K and the Curie temperature. (author)