Highly epitaxial and pure（001）-oriented CeO2 films were grown on SrTiO3（001） substrates by laser molecular beam epitaxy method without any gas ambient.Layer-by-layer epitaxial growth mode of CeO2 was confirmed by in situ reflection high-energy electron diffraction（RHEED） observations.High-resolution X-ray diffraction（HRXRD） and high-resolution transmission electron microscopy（HRTEM） results indicated the STO（100）//CeO2（100）,STO[100]//CeO2 [110] epitaxial relationship for out-of-plane and in-plane,respectively.The formation mechanism of the epitaxial film was also discussed in the light of a theoretical model.Chemical states of the LMBE ceria films were evaluated and evidences for the existence of Ce3＋and oxygen vacancies were presented.
