Gas-solid reaction of Nd(Fe, M)(12) (M = Ti, V, Mo) with H, C and N and intrinsic magnetic properties of the interstitially modified compounds

The influence of interstitial H, C and N atoms on structure and intrinsic m agnetic properties of Nd(Fe, M)(12)Z(y), (M = Ti, V, Mo; Z = H, C, N) was s tudied. Interstitial hydrogen uptake is reversible, expands the lattice and has a small, but positive effect on the intrinsic magnetic properties. Upo n C and N absorption, the ThMn12-type crystal structure is preserved in the case of M = Mo, but a decomposition process and strong growth of the conte nt of alpha-Fe is observed at temperatures above 450 degrees C for M = Ti o r V. Along with this decomposition process, a deterioration of the magnetic properties (measured at room temperature) occurs. For M = Ti or V, the hig hest values of the Curie temperature, saturation polarization and anisotrop y field were found just before the decomposition process starts. For M = Mo , the Curie temperature and anisotropy field have the highest values for Z = N, with maxima for a nitrogen concentration of 1 per formula unit. At low temperatures, the high field magnetization curves of ail carburized compou nds investigated show a metamagnetic transition when the field is applied p erpendicularly to the aligned c-axes of the epoxy bonded powders.