Color-tunable Eu3+ - or Sm3+-doped perovskite phosphors as optical temperature-sensing materials

Eu3+ or Sm3+-doped Sr2GaNbO6 perovskite phosphors are synthesized by a high-temperature solid-phase method, and their luminescence performance, energy transfer, and thermal sensitivity are studied. The results showed that Sr2GaNbO6 phosphor is an effective self-activated host, and successful doping with rare-earth ions is proven by their characteristic emission. At 332-nm excitation, both the broadband emissions from s-orbital mixing of the transition metal ions Nb5+ and Sr2+ and GaO6 groups and the sharp emissions from Eu3+ or Sm3+ ions are observed for Sr2GaNbO6:R3+ (R = Eu, Sm) phosphors, respectively. The emission color can be modulated from blue to white by regulating the doping concentration of Eu3+ or Sm3+, which is attributed to the effective energy transfer from s-orbital mixing of the transition metal ions Nb5+ and Sr2+ and GaO6 groups to Eu3+ or Sm3+. Based on the emission fluorescence intensity ratio of the s-orbital mixing of the transition metal ions Nb5+ and Sr2+ and GaO6 groups to the Eu3+ or Sm3+ ions in the range of 298-623 K, optical temperature sensing properties of Sr2GaNbO6:R3+ showed the maximum absolute and relative sensitivities are 0.0193 K-1 and 1.86% K-1 at 298 K of Sr2GaNbO6:0.018Eu(3+) phosphor, respectively, as well as 0.00862 K-1 and 1.70% K-1 at 298 K and at 623 K, respectively, of Sr2GaNbO6:0.08Sm(3+) phosphor. These results demonstrate a viable strategy to tune the emitting color and achieve optical temperature sensing in single-doped phosphors by controlling the energy transfer between the self-activated host and the activator. This strategy provides application potential for the white light-emitting diodes and non-contact thermometric multifunctional materials.