MOSSBAUER STUDY OF R(2)FE(17)C(X) (R=TB,DY) AS-QUENCHED INTERMETALLICS COMPOUNDS

Intermetallics compounds Dy2Fe17Cx (x=1.5,2.0,2.5,2.8) and Tb2Fe17Cx ( x=1.5,2.0,2.5) have been successfully prepared by the melt-spinning me thod. The x-ray-diffraction patterns and the thermomagnetic curves sho w that they are single phase with the rhombohedral Th2Zn17-type struct ure, except for Dy2Fe17C2.8 and Tb2Fe17C2.5 which have a small percent age of alpha-Fe. Fe-57 Mossbauer spectra were measured at 12 K and roo m temperature to study both the magnetic properties of R(2)Fe(17)C(x) on a local scale and the effect of the interstitial C atom on the Fe a toms. It is found that the effective hyperfine fields of the various F e sites decrease in the order 6c>18f>18h>9d. The average effective hyp erfine fields H-eff at 12 and 293 K do not change much with C concentr ation x in agreement with the moment of the Fe atoms obtained by magne tic measurements at 1.5 K. It can be concluded that the effect of C is to enhance the exchange interaction between Fe-Fe atoms, which is sen sitive to the distance of Fe-Fe atoms. The C has little influence on t he moments of Fe atoms.