Session L36 - General Poster Session II.
POSTER session, Wednesday morning, March 22
Exhibit Hall, MCC
Recent elastic modulus measurements by us on Ga stabilized \delta-Pu, as well as a critical examination of latent heat, elastic modulus and crystal structure data on this unusual metal suggest that some of the many structural phase transitions of Pu may be understood within a simple thermodynamic model. We show that the free energy of Pu in the FCC \delta phase and the BCC \epsilon phase, as well as the negative volume expansion coefficient of \delta can be understood and almost entirely accounted for by the phonon contributions to the entropy and the structure. We suggest that the behavior and stability of Pu is driven by the low elastic shear moduli that this material possesses, and that electronic structure calculations need only account for the low temperature monoclinic phase. Variation of the number of itinerant f electrons is unnecessary for an accurate description of the higher temperature phases.