Premium
Inelastic Neutron Scattering by Cerium Hydrides. III. Localized Vibrations of Interstitial Hydrogen in the F.C.C. CeH 2 Lattice
Author(s) -
Vordekwisch P.,
Hautecler S.
Publication year - 1974
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2220660223
Subject(s) - lattice (music) , octahedron , impurity , interstitial defect , hydrogen , inelastic neutron scattering , neutron , atomic physics , condensed matter physics , scattering , cerium , molecular physics , chemistry , crystallography , neutron scattering , physics , crystal structure , doping , nuclear physics , inorganic chemistry , optics , organic chemistry , acoustics
Explicit formulas have been derived for the frequencies of the localized modes of an impurity at the octahedral interstitial sites of a f.c.c. CaF 2 ‐type structure, describing the dynamics of the host lattice by short‐range central forces and assuming that the impurity interacts with the first and second neighbouring atoms of the host lattice. A threefold degeneracy is predicted. A small peak observed at 74 meV in the neutron data on CeH 1.98 is attributed to such localized modes, due to an occupation of a few percent of the octahedral sites by hydrogen atoms. A unique set of the parameter values for the coupling of the interstitial hydrogen to the atoms of the host lattice could not be derived from the position of this peak alone; a set is proposed from a comparison with the parameter values for the host lattice which have been previously determined.