Interface Structure of an Epitaxial Cubic Ceria Film on Cubic Zirconia

A cubic CeO2 (001) film of thickness equal to {approx}58 nm was epitaxially grown on Y2O3-stabilized cubic ZrO2 by oxygen plasma assisted molecular beam epitaxy (OPA-MBE). The interface was characterized using high resolution transmission electron microscopy (HRTEM). The interface exhibited coherent regions separated by equally-spaced misfit dislocations. When imaged from the[100] direction, the dislocation spacing is 3.3? 0.5 nm, which is slightly shorter than the expected value of 4.9 nm calculated from the differences in lattice constants given in the literature, but is fairly consistent with the 3.9 nm lattice mismatch measured by electron diffraction. Thus, the results presented here indicate that the lattice mismatch between the film and the substrate is accommodated mainly by interface misfit dislocations above some critical thickness.