Effect of thermal and mechanical treatments on the cathodoluminescence of tin and titanium oxides

Abstract

The luminescence of titanium oxide and tin oxide has been investigated by cathodoluminescence in the SEM, as a function of the structural changes induced by thermal treatments. The evolution of the luminescence of TiO2 rutile, anatase and mixture phase with the annealing temperature is related to the process of thermal induced grain texture and to transition of metastables phases to the stable rutile. The emission band is peaked at 480 nm for the composite phase and at 580 nm for anatase and rutile phases respectively. A broad band in the 520-560 nm region is present in the spectra of both anatase and rutile phase. Thermal annealing leads to a red shift of the luminescence emission, with the emission band peaked at around 820 nm. In sintered tin oxide the main emission bands appear centered at about 480 nm and 630 nm. The intensity of these bands increases with annealing temperature up to 1200degreesC, whereas for samples annealed at 1500degreesC these emissions are quenched. Mechanical ball milling has been used to produce nanocrystalline SnO_2 grains to investigate the influence of the presence of nanocrystals on the CL emission.