Preparation and optical properties of ThO2 and Eu-doped ThO2 nanotubes by the sol-gel method combined with porous anodic aluminum oxide template

Abstract

In this paper, we report the synthesis of thorium oxide and Eu-doped thorium oxide nanotubes for the first time using the sol-gel method in porous anodic aluminum oxide template. Transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy were applied to characterize the morphology and structure of the as-prepared nanotubes. It has been demonstrated that Eu3+ ions were homogeneously doped into the ThO2 crystal lattice. The optical properties resulting from Eu-doped products were investigated by means of photoluminescence spectroscopy. Strong visible light emissions were observed at low doping concentration, and the luminescent intensity decreased at high doping concentration. The luminescent centers were concluded to be the Eu3+ ions in the cubic (O-h) sites rather than the C-3 upsilon sites, which accounted well for the decrease of luminescent intensity at high doping concentration.