Broadband excitation of Eu3+, Bi3+ co-doped GdNbTiO6 red phosphors with good color purity

Eu3+ single-doped and Eu3+, Bi3+ co-doped GdNbTiO6 phosphors were synthesized by high temperature solid-state reaction method. The crystal structure of the samples was analyzed by means of X-ray diffraction. Strong red emission at 615 nm with good color purity was observed in GdNbTiO6: Eu3+, Bi3+ system under excitations of a wide region of ultraviolet light. Investigation on Eu3+-concentration dependent luminescence of Eu3+ single-doped samples revealed that exchange interaction between Eu3+ ions was responsible for the concentration quenching of Eu3+. Efficient energy transfers from Bi3+ to Eu3+ have been proved by using the spectra. The introduction of Bi3+ effectively extended the excitation band of Eu3+ in the near-ultraviolet region. However, it almost had no effect on the line shape and peak positions of Eu3+ emission spectra. Luminescence thermal quenching behavior was observed in both Eu3+ single-doped and Eu3+, Bi3+ co-doped GdNbTiO6 phosphors, which can be ascribed to the crossover process.