Electronic and structural studies of the hydrides of ErFe/sub 2/ from /sup 57/Fe and /sup 166/Er Moessbauer spectroscopy

Two different hydrides of the C15 Laves phase intermetallic ErFe/sub 2/ are considered. For ErFe/sub 2/ H/sub 3/./sub 65/, x-ray analyses showed the presence of an expanded C15 cubic phase and lower symmetry phase. The /sup 57/Fe mean saturated hyperfine field is 20% larger than in ErFe/sub 2/ and the /sup 166/Er hyperfine field is 15% smaller. These results coupled with previous measurements of the net moment imply that the Er--Fe coupling is not antiparallel in this hydride. For ErFe/sub 2/ H/sub 4/./sub 12/, only a structural phase consistent with trigonal lattice was detected. The Moessbauer results indicate a magnetic transition temperature between 1.7 K and 4.2 K and a drastic reduction of the Fe moment in this hydride.