Syntheses and magnetic properties of Nd/sub 3/Co/sub 13-x/Ni/sub x/B/sub 2/ borides

The effect of substitution of Ni for Co in the borides Nd/sub 3/(Co/sub 13-x/Ni/sub x/)B/sub 2/ (x=0, 1, 2, 3, 4, 5) on the crystal structure and magnetic properties has been investigated. The lattice parameter a decreases while c increases with increasing x in the range 0/spl les/x/spl les/5. The Curie temperature and saturation magnetic moment per formula unit in Nd/sub 3/(Co/sub 13-x/Ni/sub x/)B/sub 2/ decrease monotonically as the Ni concentration increases. We have observed spin-reorientation transitions at temperatures that decrease monotonically with increasing Ni concentration. It is noteworthy that the substitution of Ni has a significant effect on the magnetocrystalline anisotropy of the Co sublattice, leading to the change of easy magnetization direction of Nd/sub 3/(Co/sub 13-x/Ni/sub x/)B/sub 2/ compounds from basal plane to the c axis at room temperature when x/spl ges/2. The magnetic phase diagram of the Nd/sub 3/(Co/sub 13-x/Ni/sub x/)B/sub 2/ borides is given, and the behavior of magnetocrystalline anisotropy is analyzed by the single ion model.