NEUTRON-DIFFRACTION STUDIES OF RARE-EARTH TRANSITION-METAL NITRIDES

New high performance permanent magnets have been found as the result of nitrogenation of rare-earth-iron-based phases, including RE2Fe17 and REFe12-xTMx. Neutron diffraction has been used to study the changes in structure which accompany the nitrogenation. While some of these, like the change in lattice constants and cell volume can also be determined by x-ray diffraction, the other changes, including nitrogen location and occupation, and interatomic bond lengths can only be determined by Rietveld analysis of neutron data. These investigations and a comparison of these phases with the parent phases and with Nd2Fe14B reveal interesting trends and may provide significant insight into the physics of these materials.