Studies of Vibrational Properties in Ga Stabilized d-Pu by Extended X-ray Absorption Fine Structure

摘要

Temperature dependent extended x-ray absorption fine structure (EXAFS)spectra were measured for a 3.3 at% Ga stabilized Pu alloy over the range T= 20- 300 K at both the Ga K-edge and the Pu L_III-edge. The temperature dependenceof the pair-distance distribution widths, \sigma(T) was accurately modeledusing a correlated-Debye model for the lattice vibrational properties,suggesting Debye-like behavior in this material. We obtain pair- specificcorrelated-Debye temperatures, \Theta_cD, of 110.7 +/- 1.7 K and 202.6 +/- 3.7K, for the Pu-Pu and Ga-Pu pairs, respectively. These results represent thefirst unambiguous determination of Ga-specific vibrational properties in PuGaalloys, and indicate the Ga-Pu bonds are significantly stronger than the Pu-Pubonds. This effect has important implications for lattice stabilizationmechanisms in these alloys.