Structure and magnetocrystalline anisotropy of (Nd1−xYx)3Fe29−yCry compounds

Structure and magnetic properties of (Nd1−xYx)3Fe29−yCry compounds with x=0-1.0 and y=4-1.5 have been investigated. It is found that in an adequate annealing temperature range all the investigated compounds crystallize in the Nd3(Fe,Ti)29-type structure. However when the annealing temperature is below 1323 K, the Y3Fe27.5Cr1.5 compound crystallizes in a disordered CaCu5-type structure. Substitution of Y for Nd leads to a reduction of the lattice parameters. The Curie temperature Tc shows no clear change as the Y and Cr contents change in the above-mentioned concentration region. With increasing Y content, the easy magnetization direction changes from close to the [0 4 0] direction to the [4 0 −2] direction. The X-ray-diffraction patterns and the AC susceptibility of the (Nd1−xYx)3Fe29−yCry samples reveal a spin reorientation phenomenon for x=0-0.4 as the temperature decreases from room temperature to 77 K. The spin reorientation temperature Tsr increases monotonically with increasing Y content from 158 K for x=0 to 201 K for x=0.4.