LATTICE-PARAMETER CHANGES IN THE MIXED-OXIDE SYSTEM CE1-XLAXO2-X/2 - A COMBINED EXPERIMENTAL AND THEORETICAL-STUDY

X-Ray diffraction measurements are reported of ceramic samples of the mixed-oxide system Ce1-xLaxO2-x/2 for 0<x<0.9, where x has been determined by EDXA. The solid-state reaction forms a highly crystalline product at an ageing temperature of 1200-degrees-C. The solubility limit of La in the bulk CeO2 at this temperature has been determined as ca. 52% by monitoring the lattice parameter increase and the subsequent appearance of a second La2O3 phase. To model the experimental measurements, atomistic lattice calculations based on electron-gas shell-model potentials have been carried out to estimate the variation of the lattice parameter with La content.