Fe-57 Mossbauer spectroscopy of HoErFe17-xGaxCy compounds - art. no. 094427

Fe-57 Mossbauer studies were carried out on the phases HoErFe17-xGax (x=0-7 ) and HoErFe17-xGaxC (x = 0, 1. and 2) at 25 K and room temperature. The we ighted average hyperfine field at room temperature is found to increase ini tially for low Ga content and then decreases for phases with higher Ga conc entration. The hyperfine fields at Fe sites follow the sequence 4f(6c)>6g(9 d)>12j(18f)>12k(18h), which is determined mostly by the number of Fe and R nearest neighbors. The variation of the weighted average hyperfine field wi th temperature is found to obey T-2 behavior, suggesting the presence of si ngle-particle excitations. Insertion of carbon at interstitial sites is fou nd to increase the individual site hyperfine fields and hence an increase i n the weighted average hyperfine field. The 12j and l2k sites of Fe show si gnificant increase in isomer shift compared to other Fe sites.