Phonon densities of states of gamma-cerium and delta-cerium measured by inelastic neutron scattering

Inelastic neutron scattering spectra were measured on Ce metal at temperatu res near the fee (gamma) to bcc (delta) transition, and phonon DOS curves w ere obtained. A large difference in the phonon DOS of gamma-Ce and delta-Ce was found, and this difference accounts for a change in vibrational entrop y of (0.51 +/- 0.05)k(B) atom(-1) at the gamma-delta transition. To be cons istent with the latent heat of the gamma-delta transition, this large chang e in vibrational entropy should be accompanied by a thermodynamically-signi ficant change in electronic entropy of the opposite sign.