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 determ ined by EDXA. The solid-state reaction forms a highly crystalline prod uct at an ageing temperature of 1200-degrees-C. The solubility limit o f La in the bulk CeO2 at this temperature has been determined as ca. 5 2% by monitoring the lattice parameter increase and the subsequent app earance of a second La2O3 phase. To model the experimental measurement s, atomistic lattice calculations based on electron-gas shell-model po tentials have been carried out to estimate the variation of the lattic e parameter with La content.