TRIVALENT CE2O3 AND CEO2-X INTERMEDIATE OXIDES INDUCED BY LASER IRRADIATION OF CEO2 POWDERS

A strong non-stoichiometry of pure f c c CeO2 was induced by laser irr adiation. The increase of laser power and/or energy density had a satu rable effect on particle size growth. The possibility of CeO2 reductio n to A-Ce2O3 by laser irradiation was demonstrated. Particles of stabl e Ce7O12 phase were observed in all specimens irradiated at low laser- power densities. An epitaxial relationship between triclinic Ce11O20 a nd cubic Ce12O22 phases was found. The controversial C-Ce2O3 Phase was detected at the limits of a b c c particle. An unknown b c c phase of acicular morphology, strongly related to C-Ce2O3, was also registered . The dose dependence of CeO2 structural modifications obtained by las er irradiation as a function of laser energy density variation could b e explained by a simple defect aggregation model implying lattice defe cts (oxygen vacancies and Ce3+ ions).