Transformation of CeO2(1 1 1) to Ce2O3(0 0 0 1) films

An ordered CeO2(1 1 1) film has been grown on Re(0 0 0 1) substrate and studied by X-ray photoelectron spectroscopy and low-energy-electron diffraction. The results indicate that Ce4+ cations are reduced to Ce3+ by heating the cerium dioxide films in ultrahigh vacuum at 1000 K, and the Ce3+ cations can be re-oxidized to Ce4+ at 700 K in oxygen ambience. That reduction and re-oxidation caused by oxygen release and storage results in a formation of oxygen vacancies on the ceria surface and the CeO2(1 1 1)–Ce2O3(0 0 0 1) transition.