PNNL

Abstract

Cubic-CeO2 and -Fe2O3 thin films have been epitaxially grown on yttria-stabilized ZrO2 and -Al2O3 substrates, respectively, by oxygen plasma assisted molecular beam epitaxy (OPA-MBE). The interface structural features between the films and the substrates were characterized by Rutherford backscattering spectrometry (RBS), high resolution transmission electron microscopy (HRTEM), and x-ray diffraction (XRD). RBS channeling spectra for both CeO2/ZrO2 and Fe2O3/Al2O3 show interface disorder-related scattering peaks. It is believed that the observed interface disorder-related scattering peaks on RBS spectra are attributed to the interface misfit dislocations. Cross sectional HRTEM reveals that interfaces of both systems are similarly characterized by coherent regions that are separated by misfit dislocations periodically distributed along the interface. The experimentally observed dislocation spacings are approximately consistent with those calculated from the lattice mismatch, implying that the lattice mismatch is accommodated mainly by interface misfit dislocations above the critical thickness.