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

Abstract

An optical thermometer Bi 3+ , Eu 3+ co-doped Sr 3 La 2 Ge 3 O 12 (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: Bi 3+ phosphor exhibits the 3 P 1 → 1 S 0 blue luminescence of Bi 3+ peaked at 400 nm and SLGO: Eu 3+ phosphor shows the 5 D 0 → 7 F 2 red luminescence of Eu 3+ peaked at 612 nm. The ET behavior was proved by spectrum overlap between the PL spectrum of Bi 3+ and PLE spectrum of Eu 3+ . Moreover, the decay time of Bi 3+ could be verified the conclusion. Under UV excitation of 291 nm, the maximal value of absolute sensitivity ( S a ) of SLGO: Bi 3+ , Eu 3+ was 0.079 %K −1 at 573 K, and relative sensitivity ( S r ) was 0.831 %K −1 at 473 K. The results proved that SLGO: Bi 3+ , Eu 3+ phosphor could have a good performance in the field of optical thermometer. • The Sr 3 La 2 Ge 3 O 12 : Bi 3+ , Eu 3+ phosphors can conquer the inherent defects of TCL-based phosphors. • The Sr 3 La 2 Ge 3 O 12 : Bi 3+ , Eu 3+ phosphors have high temperature sensitivity and signal discriminability. • The ET behavior and temperature-dependent sensing properties of Bi 3+ and Eu 3+ are discussed.