X-RAY AND MOSSBAUER STUDIES OF SM-FE-NB(ZR) (2 17/2) ALLOYS AND THEIRNITRIDES/

Sm-Fe and Sm-Fe-(Nb or Zr) alloys, with stoichiometry RE:TM = 2:17 wer e prepared in ribbon form, using the melt spinning technique. The samp les then were annealed and nitrated. X-ray diffraction and Mossbauer s pectroscopy were used to study the samples. The presence of Nb(Zr) ato ms stabilize the TbCu7 structure, while the samples without substituti ons crystallize in the Th2Zn17-type structure. The hyperfine parameter s for the corresponding phases are deduced from analysis of Mossbauer spectra in the temperature range 15-300 K. At 300 K the mean hyperfine fields are 241 and 219 kOe for the Nb and Zr phases, respectively. Th e Curie temperature of Sm2Fe17 is higher than that of the intermetalli c compound Sm2Fe17 prepared by the are melting technique, and the Curi e temperatures of the TbCu7-type phases are in the range 200-230 degre es C. Remarkable enhancements in the coercive fields of the 1:7 nitrid e products are observed.