The Y3 (Fe0.969-xMo0.031Gax) 29 (X≤0.15) and Sm3 (Fe0.966-xMo0.034Gax) 29 (X≤0.10) compounds have been successfully prepared. By means of X-ray diffraction analysis, it was shown that all of the investigated compounds crystallized in the Nd3 (Fe, Ti) zg-structure. The effects of Ga substitution for Fe in the Y3 (Fe0.969Mo0.031) 29 and Sm3 (Fe0.966Mo0.034) 29 compounds on the lattice parameters, and intrinsic magnetic properties including Curie temper-atures, saturation magnetization, and magnetocrystalline anisotropy of the investigated compounds are reported.

The iron-rich ternary intermetallic compound Nd3 (Fe, Mo) 29 with the Nd3 (Fe, Ti) 29-type monoclinic structure and its nitride were prepared. After nitrogenation, the nitride retains the structure of the parent compound, but the unit-cell volume of the nitride is 5.9% greater than that of the parent compound. The Curie temperature of Nd3 (Fe, Mo) 29 nitride is 70.9% higher than that of the parent compound and the saturation magnetization of the nitride is about 6.6% (at 4.2K) and 23.7% (at 300K) higher than that of the parent compound. The anisotropy of the nitride is similar to that of parent compound, which exhibits plane anisotropy.

Sm3 (Fe, Mo) 29Nx nitride has been synthesized at 823K for 2.5h by gas phase reaction under 1 atm of nitrogen. The nitride retains the structure of parent compound. The unit cell volume of the nitride is 4.7% greater than that of the parent compound. Introduction of nitrogen leads to an increase of Curie temperature Tc from 445K for the parent to 704K for the nitride, and an increase of saturation magnetization Ms from 135Am2/kg for the parent to 152Am2/kg for the nitride at 4.2K, and from 107Am2/kg for the parent to 137Am2/kg for the nitride at 300K. The nitride exhibits uniaxial anisotropy with an anisotropy field Ba of 20.5T at 4.2K and 14.6T at 300K.

The optimum compositions and annealing conditions of the preparing single-phase R3 (Fe, Mo) 29 (R=Tb and Dy) are reported. The structural characterization by X-ray powder diffraction provides evidence for a Nd3 (Fe, Ti) 29-type compound with the space group A2/m. The Curie temperatures Tc are 437 K for Tb3 (Fe, Mo) 29 and 408K for Dy3 (Fe, Mo) 29. The saturation magnetization Ms values are 77.5Am2/kg at 4.2K and 70.4Am2/kg at 300K for Tb3 (Fe, Mo) 29, and 73.0Am2/kg at 4.2K and 65.2Am2/kg at 300K for Dyz (Fe, Mo) 29.

The effective exchange coupling parameters JFeFe in the Fe sublattice and JRFe between the R and Fe sublattices have been calculated based on a mean field approximation according to the experimental values of the Curie temperatures of R3 (Fe, M) 29 (R=rare earth, M=V, Ti and Mo). JFeFe is largest when M=V and smallest when M=Mo, but JRFe is largest when M=Ti and smallest when M=Mo for the same R and different M in the R3 (Fe, M) 29 compounds.