XRD patterns of the starting TiO2 (sample A) and TiO2-xNx (sample B) heated to various temperatures: (1) starting TiO2 prepared from anatase ST 01, Ishihara Ltd., Japan (sample A), (2) TiO2-xNx (sample B) prepared by heating sample A in a flow of NH3 at
575°C/3 h, and (3) TiO2-xNx (sample B) annealed at 950°C.
