Exp 57 Fe Impurity Atom Lattice Dynamics and Systematics in Group V and VI Host Metals

摘要

The Moessbauer recoil-free fraction f and thermal shift have been measured for very dilute exp 57 Fe impurities in body-centered cubic V, Nb, Mo, Ta, and W host metals in the range 4 to 860 exp 0 K. These experimental quantities have been interpreted in terms of an impurity-atom lattice-dynamical model of Mannheim where the important parameter gamma /sub ih// gamma /sub hh/ is a measure of the coupling of the impurity atom to the host lattice relative to the corresponding coupling in the pure host lattice. Values of gamma /sub ih// gamma /sub hh/ for each host from the f-value data were obtained and, independently, from the shift data, and for each host rather good agreement is obtained. The general trend of the data shows that for neighboring hosts of the same row of the periodic table, the relative exp 57 Fe impurity binding is stronger for the Group V host than for the Group VI host. The results also support a previous conjecture that the nearest-neighbor binding between the impurity and the host should be proportional to a geometric mean of the nearest-neighbor couplings for a lattice consisting entirely of impurity atoms and for a lattice of host atoms only. (ERA citation 02:020475)