Simulation of lattice thermal expansion behaviour of Th_(1-x)Pu_xO_2 (0.0<=x<=1.0) using CeO_2 as a surrogate material for PuO_2

摘要

Earlier it was shown that ThO_2 and CeO_2 form almost an ideal solid solution throughout the homogeneity range. In this manuscript, we report the lattice thermal expansion behaviour of Th_(1-x)Ce_xO_2 (0.0<=x<=1.0) in the temperature range from ambient to 1473 K investigated by high-temperature X-ray diffraction. The coefficient of average lattice thermal expansion (alpha_a) progressively increases on going from ThO_2 to CeO_2 in Th_(1-x)Ce_xO_2. The typical alpha_a values of ThO_2, Th_(0.5)Ce_(0.5)O_2 and CeO_2 were found to be 9.54X10~(-6), 10.62X10~(-6) and 11.58X10~(-6) K~(-1), respectively in the temperature range 293-1473 K. Thus the substitution of Ce~(4+) at Th~(4+) sites in ThO_2 has a systematic influence on the thermal expansion behaviour. These results will be useful in simulating the thermal expansion behaviour of thoria-plutonia mixed oxides.