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

Pure cubic zirconia (<i>c</i>-ZrO₂) is unstable at room temperature. We achieved the epitaxial formation of <i>c</i>-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 <i>c</i>-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[1 -1 0]//ZrB₂[2 -1 -1 0], 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. [DOI: 10.1380/ejssnt.2015.111]