Bright visible luminescence of self-organized ZrO2 nanotubes

Self-organized nanotubular layers of ZrO2 are electrochemically grown by tailored anodization in an (NH4)2SO4 electrolyte containing small amounts of fluoride ions. The structure and morphology of these nanotubular layers were characterized by electron microscopy. XRD-measurements revealed anodic ZrO2 films to be crystalline. Luminescence properties were investigated by photoluminescence and cathodoluminescence measurements. In both methods a very bright white luminescence of as-grown ZrO2 nanotubes is observed. While the origin of this luminescence is not entirely clear, the findings may provide a path towards optoelectronic applications of ZrO2 nanotubes.