Epitaxial Growth of CeO2 Buffer Layers on IBAD-Textured MgO Templates by Pulsed Laser Deposition

Epitaxial growth of CeO
₂
buffer layers on the ion-beam assisted deposition (IBAD)-textured MgO templates could be successfully achieved by an annealing heat treatment prior to CeO
₂
deposition by pulsed laser deposition (PLD). The annealing process was performed in a tube furnace (ex-situ annealing) or in a PLD chamber (in-situ annealing). Analyses by x-ray photoelectron spectroscopy on the surface of ex-situ annealed MgO single crystals revealed that Mg(OH)
₂
formed on the MgO surface in air was gradually decomposed into MgO with increasing annealing temperature and period. The CeO
₂
layer on the IBAD MgO template ex-situ annealed for 6 h at 750 °C was only c-axis oriented in comparison with that on the nonannealed IBAD MgO template. However, some 45°-rotated grains were observed in the CeO
₂
layer on ex-situ annealed IBAD MgO template. In contrast, in-situ annealing for 1 h at 800 °C was found effective to grow CeO
₂
layer with a cube-on-cube orientation, suggesting that Mg(OH)
₂
and MgCO
₃
phases on the MgO surface were fully decomposed into MgO phase with (001) (a//[100]) orientation. TEM analyses supported that a high degree of biaxial alignment of CeO
₂
layer was deposited on in-situ annealed IBAD MgO template.