EXISTENCE RANGE, STRUCTURAL AND MAGNETIC-PROPERTIES OF ND-3 FE27.5TI1.5-YMOY AND ND3FE27.5TI1.5-YMOYNX (0.0-LESS-THAN-OR-EQUAL-TO-Y-LESS-THAN-OR-EQUAL-TO-1.5)

A series of alloys with the composition Nd(3)Fe(27.5)Ti(1.5-y)MO(y) (0 less than or equal to y less than or equal to 1.5) and the Nd-3(Fe,Ti)(29)-type structure have been synthesized. The X-ray diffraction pattern of these compounds can be indexed in the monoclinic symmetry with lattice parameters of a = 10.6382(5) Angstrom, b = 8.5892(4) Angstrom c = 9.7456(5) Angstrom and beta = 96.930(2)degrees and the structure can be described in the A2/m space group (Z = 2). This is a minimal non-isomorphic supergroup of P2(1)/c. With this description the number of Fe sites is eleven. The Curie temperature depends on the Ti, Mo concentration and increases from 400 to 437 K with increasing Ti. The room temperature saturation magnetization for the y = 0 sample is 139.6 A m(2)/kg and the anisotropy field 3.7 T. After nitrogenation a lattice expansion of 5.3% is observed. Four N atoms per formula unit and their probable sites (4i and 4f) are predicted. An empirical model is proposed for the calculation of the number of the N atoms for all phases halving a superstructure relation to the 1:5 phase. The Curie temperature increases by 280 K reaching 663 to 712 K depending on the Ti:Mo ratio. The room temperature saturation magnetization of the y = 0 sample becomes 170.6 A m(2)/kg and the anisotropy field 8.0 T after the nitrogenation process. X-ray powder diffraction patterns of magnetically aligned powder samples of the parent anti the nitrided compound indicate the prescence of an easy-cone-type anisotropy. The calculated room temperature anisotropy constants, K-1 = -1.80 MJ/m(3), K-2 = 1.86 MJ/m(3) for the parent y = 0 sample and K-1 = -5.17 MJ/m(3), K-2 = 3.57 MJ/m(3) for the nitrided one, confirm this assumption.