Mössbauer spectra of Nd2Fe14B and related compounds

Mössbauer spectra and ac susceptibility data on Nd₂Fe_{1 4} B with substitution of Pr or Sm for Nd indicate that the spinreorientation temperature is depressed by Pr substitution but increased in alloys containing Sm so that it occurs at roomtemperature for Nd_{1 2}Sm₅Fe_{7 6}B₇. In the Nd end-member, the onset of the transition appears about 210 K although the main reorientation is at 134 K. Nickel shows no marked site preference: its effects are to increase slightly the Curie temperature and reduce the iron moment.