An estimate of the high temperature, metal rich phase boundary of plutonium sesquioxide

The composition of the metal rich phase boundary of plutonium sesquioxide has been estimated at 1400 K by comparing the calculated, equilibrium pressure of Pu(g) over the solid solution range of the sesquioxide with the reported Pu(g) pressure over the mutually saturated system, Pu(liquid,O2 saturated)+〈Pu2O3−x〉hex. The Pu(g) pressure at the previously recommended metal rich phase boundary is shown to be low by a factor of nearly 3000. The newly estimated metal rich phase boundary results in a homogeneity range for the sesquioxide that is larger by a factor of 1.8.