Preparation and luminescence of nano-sized In(2)O(3) and rare-earth co-doped SiO(2) thin films.

The sol-gel method was used to prepare SiO(2) thin films co-doped with In(2)O(3) nano-particles and Eu(3+). The formation of nano-sized In(2)O(3) particles after annealing at 900 °C was confirmed by the x-ray diffraction technique. A novel phase transition from a hexagonal rhombic centered to a body centered cubic structure of In(2)O(3) nano-particles was observed at around 1100 °C. It is found that the particle size and the particle density of In(2)O(3) can be tuned by changing the annealing temperature and the indium doping concentration, respectively. The characteristic emission bands from Eu(3+) ions can be observed at room temperature and the luminescence intensity is increased 20 times by introducing In(2)O(3) nano-particles into Eu(3+)-doped silica films. The integrated luminescence intensity was gradually enhanced by increasing the In(3+) concentration, suggesting effective energy transfer from nano-sized In(2)O(3) to Eu(3+) ions.