Effect of different temperatures to remove reduction gas on the photoluminescence properties of Eu-doped Li (Ba Sr )SiO phosphors.

In this study, Eu-doped Li (Ba Sr )SiO powders (x = 0, 0.2, 0.4, and 0.6) were synthesized at 850°C in a reduction atmosphere (5% H + 95% N ) for a duration of 1 h using a solid-state reaction method. The reduction atmosphere was infused as the synthesis temperature reached 850°C, and was removed as the temperature dropped to 800-500°C. Li (Ba Sr )SiO (or Li BaSiO ), (Ba,Sr) SiO (or BaSiO ), and Li SiO phases co-existed in the synthesized Eu-doped Li (Ba Sr )SiO powders. A new finding was that the reduction atmosphere removing (RAR) temperature of the Li (Ba Sr )SiO phosphors had a large effect on their photoluminescence excitation (PLE) and PL properties. Except for the 800°C-RAR-treated Li BaSiO phosphor, PLE spectra of all other Li (Ba Sr )SiO phosphors had one broad emission band with two emission peaks centred at ~242 and ~283 nm; these PL spectra had one broad emission band with one emission peak centred at 502-514 nm. We showed that the 800°C-RAR-treated Li BaSiO phosphor emitted a red light and all other Li (Ba Sr )SiO phosphors emitted a green light. Reasons for these results are discussed thoroughly.