Structure and magnetic properties of Nd-2(Co, Mn)(17) compounds

X-ray diffraction (XRD) and magnetization measurements were carried out to investigate the effect of Mn substitution for Co on the structure and magne tic properties of Nd2Co17-xMnx compounds with x = 0 - 8. XRD patterns show that all samples are single phase with the rhombohedral Th2Zn17-type struct ure except the samples with x = 6 - 8 which contain a small amount of impur ity. The substitution of Mn for Co leads to a monotonic increase in unit ce ll volume. The saturation magnetic moment first increases slightly for x = 0 - 2 and then decreases quickly with increasing Mn concentration. The Curi e temperature T-C decreases monotonously with increasing Mn content. XRD me asurements on magnetically aligned samples with x = 0 - 6 exhibit an easy-p lane type of magnetocrystalline anisotropy at room temperature. For x = 1 - 5, a spin-reorientation transition is observed above room temperature in M -T curve, This is explained by that Mn substitution for Co leads to a chang e of the magnetocrystalline anisotropy of the 3d-sublattice from basal plan e to c-axis and to tempera in re-induced competition between the 3d-sublatt ice and Nd-sublattice anisotropy, The magnetic phase diagram is given. The magnetocrystalline anisotropy field mu H-0(A) is found to decrease sharply with Mn substitution for x less than or equal to 2 and then remains nearly unchanged with increasing Mn concentration, the anisotropy constant K-1 is negative for x = 1 - 5 with the absolute value decreases sharply. (C) 2001 Elsevier Science B.V. All rights reserved.