MOSSBAUER STUDY OF PERMANENT-MAGNET MATERIALS - SM2FE17-XALX COMPOUNDS

The Fe-57 Mossbauer spectra of Sm2Fe17-xAlx, where x=0, 1.0, 2.0, 3.0, and 4.0, have been measured at room temperature and analyzed. The ter nary compounds Sm2Fe17-xAlx have the rhombohedral Th2Zn17 structure. M ossbauer measurements showed that all the compounds studied were ferro magnetic. The average hyperfine field was found to decrease with the i ncreasing aluminum concentration, which is in qualitative agreement wi th magnetic measurements. The decrease in the average hyperfine field was from 224 kOe at x=0 to 174 kOe at x=4. By fitting the spectra we f ound that the hyperfine fields for the iron sites decrease in the orde r 6c, 9d, 18f, and 18h. The measured average isomer shift relative to alpha-iron was found to increase linearly with x. Analysis of the spec tra showed that Al atoms occupy the 6c, 18h, and 18f, but not 9d, Fe s ites and the fraction of occupancy of Al was found to depend on x.