Effect of Eu doping on room temperature phase and phase transition of Sr2SiO4:Eu2+ phosphor synthesized by polymerized complex method

Abstract

Eu2+ activated silicate phosphor, Sr2SiO4:Eu2+ were synthesized by polymerized complex method to investigate the effect of Eu doping on room temperature phases. Firstly, synthesis condition for β phase was optimized and found that β-Sr2SiO4:Eu2+ phosphors can be obtained at reduction temperature of 1150 °C using HCl, which provide SrCl2 flux during synthesis process. The characterization for various Eu concentration of Sr2SiO4:Eu2+ phosphors show that pure β-Sr2SiO4:Eu2+ phosphors were obtained at 1%, 3% and the samples which are almost in β phase can be achieved until 5%. Temperature dependence of crystal structure and PL properties of Sr2SiO4:Eu2+ (3%) phosphors were also characterized to investigate the phase transition and thermal hysteresis between β and α′ phase. Phase transition between β ↔ α′ phase was observed from XRD around 60 °C–100 °C and change in PL spectra owing to phase transition was observed around same temperature range. The further analysis show that the thermal hysteresis between β → α′ and α’→ β directions of Sr2SiO4:Eu2+ (3%) phosphors were about 40 K, which was much larger than the reported thermal hysteresis of undoped Sr2SiO4.