Thermal quenching(TQ)at elevated temperature is a major factor affecting the luminescent intensity and efficiency of phosphors.Improving the thermal stability of phosphors and weakening the TQ effect are of significan...Thermal quenching(TQ)at elevated temperature is a major factor affecting the luminescent intensity and efficiency of phosphors.Improving the thermal stability of phosphors and weakening the TQ effect are of significance for the high-quality illumination of phosphor-converted WLEDs.Here,a novel red-emitting phosphor K_(2)Zn(PO_(3))_(4)∶Mn^(2+)is synthesized by standard high temperature solid state reaction in ambient atmosphere,which is a new member of self-reduction system.An effective synthesis strategy is proposed to optimize its photoluminescent performances.Combined with X-ray photoelectron spectroscopy and X-ray absorption fine structure spectroscopy,oxygen vacancy defects introduced by Mn doping are proved to play an important role in the transition of Mn^(4+)→Mn^(2+).Thermoluminescence analysis reveals that the distribution of trap levels,especially the deep ones,is effectively regulated by the controllable crystallization and significantly affect the thermal stability of phosphors.Then a defect-assisted model is proposed to address the inner mechanism of the phenomenon.The carriers trapped by deep trap levels can be released under the high-temperature stimulus,which return back to the luminescent centers and participate in the radiative recombination to improve thermal stability.This study provides a new crystallographic idea and theoretical support for obtaining luminescent materials with high thermal stability.展开更多
文摘Thermal quenching(TQ)at elevated temperature is a major factor affecting the luminescent intensity and efficiency of phosphors.Improving the thermal stability of phosphors and weakening the TQ effect are of significance for the high-quality illumination of phosphor-converted WLEDs.Here,a novel red-emitting phosphor K_(2)Zn(PO_(3))_(4)∶Mn^(2+)is synthesized by standard high temperature solid state reaction in ambient atmosphere,which is a new member of self-reduction system.An effective synthesis strategy is proposed to optimize its photoluminescent performances.Combined with X-ray photoelectron spectroscopy and X-ray absorption fine structure spectroscopy,oxygen vacancy defects introduced by Mn doping are proved to play an important role in the transition of Mn^(4+)→Mn^(2+).Thermoluminescence analysis reveals that the distribution of trap levels,especially the deep ones,is effectively regulated by the controllable crystallization and significantly affect the thermal stability of phosphors.Then a defect-assisted model is proposed to address the inner mechanism of the phenomenon.The carriers trapped by deep trap levels can be released under the high-temperature stimulus,which return back to the luminescent centers and participate in the radiative recombination to improve thermal stability.This study provides a new crystallographic idea and theoretical support for obtaining luminescent materials with high thermal stability.
