/sup 57/Fe Mossbauer investigation of R/sub 2/(Fe/sub 1-x/Co/sub x/)/sub 17/N/sub y/ (R=rare earth, x

The effects of different contents of nitrogen in both Pr/sub 2/Fe/sub 17/ and Nd/sub 2/Fe/sub 17/ and of cobalt in both Nd/sub 2/Fe/sub 17/ and Nd/sub 2/Fe/sub 17/N/sub 2.2/ are investigated by means of Mossbauer spectroscopy and thermal magnetic analysis. The results confirm that either nitrogen or cobalt increases the hyperfine field (B/sub hf/) as well as the Curie temperature (T/sub c/) of the material. The hyperfine parameters for nominal contents of nitrogen above y=1.5 are the same as those observed in fully nitrided samples. The data also reveal that the combination of N and Co produces an additional increase of T/sub c/. The same behavior is observed in B/sub hf/ of Nd/sub 2/(Fe/sub 1-x/Co/sub x/)/sub 17/N/sub 2.2/ in the range 0>