Mössbauer study of intercalation modified compounds R2Fe17 (R=Y, Sm)

Mössbauer studies were carried out at 77 K in two series of R2Fe17 compounds with a magnetic (Sm) and nonmagnetic (Y) rare-earth, intercalated with H, C, and N. The increase in hyperfine field is largest at the 12j(18f) sites for R2Fe17H3.7 and R2Fe17N2.3. While the lattice expansion in R2Fe17C2 is similar to that in the nitrides and hydrides, the small change in hyperfine fields at the 12j(18f) and 12k(18h) sites indicates that the presence of neighboring carbon largely cancels the moment increase associated with the volume increase. For R2Fe17 carbonitrides, a single, sharp magnetic transition indicates a uniform compound. However, Mössbauer spectra suggest the existence of both C-rich and N-rich precipitates in the carbonitrides whose average hyperfine fields and isomer shifts scale with the nitrogen to carbon ratio.