Photoluminescence performance of thulium doped Li_4SrCa(SiO_4)_2 under irradiation of ultraviolet and vacuum ultraviolet lights

摘要

In this work, we synthesized Tm~(3+) doped Li_4SrCa(SiO_4)_2 phosphors and investigated their photo-luminescence properties under the excitation of ultraviolet and vacuum ultraviolet lights. The crystal structure analysis and variation of cell parameters confirm that Tm~(3+) ions have been successfully doped in the structure of Li_4SrCa(SiO_4)_2 host by occupying the sites of Ca~(2+) with the coordination number of 6. The luminescence results suggest that Li_4SrCa(SiO_4)_2:Tm~(3+) is a good blue-emitting phosphor when excited by ultraviolet and vacuum ultraviolet irradiations. In addition, it is observed that there is nearly no degradation for Li_4SrCa(SiO_4)_2:Tm~(3+) after undergoing thermal and irradiation treatments. Possible mechanisms for the luminescence processes are proposed on the basis of the discussion of excitation and emission spectra. In particular, the emission color of Li_4SrCa(SiO_4)_2:Tm~(3+) by excitation of 147 and 172 nm irradiations is very close to the standard blue color, suggesting that it could be potentially applied in plasma displav panels and mercury-free fluorescence lamps.