Structural and magnetic properties of Y3(Fe1 − xCox)27.5V1.5 (0 ≤ x ≤ 0.4)

The structural and magnetic properties of Y3(Fe1 − xCox)27.5V1.5 compounds with x = 0-0.4 have been investigated. The main phase formed was that of Nd3(Fe, Ti)29-type structure (3:29) with a significant amount of the ThMn12-type structure (1:12) as a secondary phase (25-35 wt.%). The unit cell volume is decreasing with x; the cell parameters show anisotropic decrease with the Co content (parameter a decreases faster than b, c). The Curie temperature increases monotonically with x from 425 to 858 K. The substitution of Co for Fe results in a change of the magnetocrystalline anisotropy of the transition metal sublattice and changes the easy magnetization direction of Y3(Fe1 − xCox)27.5V1.5 compounds within or very near to the basal plane of the parent CaCu5-type structure (1:5), i.e., perpendicular to the [2 0 4] direction of the monoclinic Nd3(Fe, Ti)29-type structure. The weighted average hyperfine field increases by increasing the Co content.