The binding energy of Sm 3d5/2 for10mol% Sm-doped TNT(1088.3eV)was chemically shifted from that of Sm2O3 (1087.5 eV),showing that Sm3+ existed in theTiO2 lattice. Sm3+-doped TNTs clearly exhibited red fluorescence, corresponding to the dopedSm3þ ion in the TNT lattice. The Sm-doped TNT excitation spectrum exhibited a broad curve, which was similar to the UV–vis optical absorption spectrum. Thus ,it was considered that the photoluminescence emission of Sm3þ-doped TNT with UV-light irradiation was caused by the energy transfer from the TNT matrix via the band-to-band excitation of TiO2 to theSm3þ ion.