Dual emitting from Bi3+/Eu3+ co-activated Sr3La2Ge3O12 phosphor for optical thermometry

An optical thermometer Bi3+, Eu3+ co-doped Sr3La2Ge3O12 (SLGO) phosphor with dual-emitting centers was synthesized in high-temperature condition. The X-ray diffraction patterns, SEM, EDS, luminescent properties and optical temperature sensing characteristics were exhaustive investigated. Under UV excitation, the SLGO: Bi3+ phosphor exhibits the 3P1→1S0 blue luminescence of Bi3+ peaked at 400 nm and SLGO: Eu3+ phosphor shows the 5D0→7F2 red luminescence of Eu3+ peaked at 612 nm. The ET behavior was proved by spectrum overlap between the PL spectrum of Bi3+ and PLE spectrum of Eu3+. Moreover, the decay time of Bi3+ could be verified the conclusion. Under UV excitation of 291 nm, the maximal value of absolute sensitivity (Sa) of SLGO: Bi3+, Eu3+ was 0.079 %K−1 at 573 K, and relative sensitivity (Sr) was 0.831 %K−1 at 473 K. The results proved that SLGO: Bi3+, Eu3+ phosphor could have a good performance in the field of optical thermometer.