Lattice dynamics of [alpha]-cerium

Abstract

<p>We investigated the lattice dynamics of the fcc (alpha)-phase of cerium metal using inelastic neutron scattering techniques. This phase of cerium is an example of a mixed-valent system. Various physical properties of (alpha)-Ce suggest that there may be coupling between the phonons and the f d transitions associated with the mixed-valence phenomenon. Our measurements of the dispersion curves provide important information about the electron-phonon interaction in this phase of cerium. These studies were not performed in the past because single crystals of (alpha)-Ce were not available. We were able to prepare a single (alpha)-Ce crystal using a high temperature-high pressure technique. The sample was of sufficient size for inelastic neutron scattering experiments, but the measurements were com- plicated because of the large mosaic spread (('(TURN))7.0(DEGREES)) of the crystal. It was possible, however, to obtain a set of dispersion curves along the 00(xi) , (xi),(xi),0 and (xi),(xi),(xi) symmetry directions. Comparison of the dispersion curves with those of fcc (gamma)-Ce indicate that the;branches exhibit anomalous features which may be related to the mixed-valence effects; ('1)DOE Report IS-T-1162. This work was performed under contract No. W-7405-Eng-82 with the U.S. Department of Energy.</p>