Cubic Zirconia Crystalline Surface Oxide Epitaxial Formation on ZrB₂(0001) Confirmed by Circularly-Polarized-Light Photoelectron Diffraction

Abstract

Pure cubic zirconia (c-ZrO2) is unstable at room temperature. We achieved the epitaxial formation of c-ZrO2 crystalline surface oxide islands on ZrB2(0001) by annealing the substrate without sample cleaning at 950• C under ultrahigh-vacuum conditions. The interface structure at the c-ZrO2 islands and the ZrB2(0001) substrate was investigated using element-specific circularly-polarized-light photoelectron diffraction, angle-resolved X-ray photoelectron spectroscopy, and reflection high-energy electron diffraction (RHEED). The ZrO2(111) islands was a twin crystal oriented in ZrO2[110]//ZrB2 [2110], and was stable up to around 1500• C. The Zr-Zr distance of ZrB2 bulk and that of ZrO2 (111) agree with at the ratio of 8 to 7.