Luminescence of anatase TiO2 single crystals annealed in oxygen atmosphere

Anatase single crystals were grown by chemical vapor transport method. As-grown crystal with blue color was annealed in oxygen atmosphere. The crystal changes its color to yellow or colorless depending on the annealing. A broad luminescence band at around 2.3 eV was observed in as-grown and annealed anatase, but the line shape is changed by the annealing condition as well as excitation energy. The band will be decomposed into three Gaussian-type bands. Origin of the three emission bands is discussed. (C) 2000 Elsevier Science B.V. All rights reserved.