The Debye–Waller factor of stabilized [formula omitted]-Pu

Abstract

The Debye–Waller factor has been calculated for stabilized δ -phase plutonium with 5% aluminum. A quasi-harmonic Born–von Kárman force model with temperature dependent phonon frequencies was used to calculate the mean-square thermal atomic displacement from absolute 0 to 800 K. Implementation of the observed anomalous softening of the long wavelength phonons with increasing temperature cannot account for the softening of the measured thermal parameter at high temperatures nor for its rather high value at low temperatures. The implications for diffraction measurements on δ -phase stabilized plutonium alloys are discussed.