Li2CO3/K3PO4复合助熔剂对新型Y2O2S：0.09Ti长余辉磷光体发光性能的影响

采用高温还原法合成了一种新型无稀土掺杂Y₂O₂S:0.09Ti长余辉发光材料。基于助熔剂种类对长余辉发光材料特性的重要作用,选择了对余辉衰减初期和后期余辉强度有明显作用的Li₂CO₃和K₃PO₄两种助熔剂,研究了不同配比(以下用x表示,x=Li₂CO₃/(Li₂CO₃+K₃PO₄))的复合助熔剂对Y₂O₂S:0.09Ti磷光体晶体结构和发光性能的作用,以获得具有较好综合发光性能的Y₂O₂S:0.09Ti磷光体。采用PL光谱和余辉测试仪对材料的发光特性进行了表征,用XRD研究了其晶体结构的变化。XRD结果表明,在复合助熔剂范围内(x=0~1.0)均可获得单相性的Y₂O₂S:0.09Ti磷光体。同时发现复合助熔剂比例不同制备的样品中,Y₂O₂S:0.09Ti磷光体晶体择优取向也发生明显的变化,且高比例Li₂CO₃有助于Y₂O₂S:0.09Ti磷光体的晶体形成。复合助熔剂比例x对样品的激发峰与发射谱主峰位置(565nm)基本没有影响;但助熔剂比例x对发射峰强度则有明显影响,随着x增加,该磷光体的发光强度先增后减,在x=0.8时发光强度最大。

Influence of Li2CO3/K3PO4 Flux Ratio on the Luminescent Properties of Y2O2S: Ti Phosphor

As the added flux has much more severe effect on the luminescence properties,the influence of Li₂CO₃/(Li₂CO₃+K₃PO₄) flux ratio x(x= Li₂CO₃/(Li₂CO₃+K₃PO₄)) on the luminescence properties of Y₂O₂S:0.09Ti phosphor has been investigated to obtain the best luminescence and afterglow intensity.The composite flux of Li₂CO₃ plus K₃PO₄ was selected because Li₂CO₃ and K₃PO₄ flux have been demonstrated in previous study to improve the afterglow intensity in the beginning stage and long time stage,respectively.PL spectra and afterglow measurement were used to analyze the effect of flux ratio on the luminescence and after glow properties of Y₂O₂S:0.09Ti phosphor.And XRD measurements were carried out to verify the crystal structure.XRD results showed that the single phase Y₂O₂S:0.09Ti phosphor could be obtained when flux ratio x increases from 0 to 1.0,while the grain growth orientation may change obviously.The fact that excitation spectra are similar in all flux range demonstrates that the flux ratio has little effect on the excitation process.Nevertheless,the emission spectra showed that the intensity of emission peak at 565 nm depended greatly on the flux ratio.Luminescence intensity of Y₂O₂S:Ti phosphor increased with an increase of Li₂CO₃ ratio x,then reduced as x over 0.8.On the other hand,afterglow brightness of Y₂O₂S:Ti was enhanced at appreciate Li₂CO₃/(Li₂CO₃+K₃PO₄) ratio of about 0.4 with an enhanced afterglow brightness(9.1 mcd·m^-2) at(decay) time of 30 min.This value is about four times as that of single Li₂CO₃ doping(2.4 mcd·m^-2),and two times as that of single K₃PO₄ doping(4.3 mcd·m^-2).Above results about the effect of flux ratio on luminescence after glow properties could be used to adjust the overall properties of Y₂O₂S:0.09Ti phosphor.The best afterglow with yellow color is obtained at appreciate Li₂CO₃/(Li₂CO₃+K₃PO₄) ratio of about 0.4,and its afterglow can last over 5 h with recognizable intensity level(0.32 mcd/m²) after the removal of the excitation light.