(Zn1-x,Mgx)2GeO4∶Mn^2＋的荧光以及长余辉发光性能

Photoluminescence and Long-lasting Phosphorescence Characteristics of (Zn_(1-x),Mg_x)_2GeO_4∶Mn^(2+)

采用高温固相法制备了一系列(Zn_(1-x),Mg_x)_2GeO_4∶Mn^(2+)(0≤x≤0.25)绿色荧光粉,并研究了Mg离子对(Zn_(1-x),Mg_x)_2GeO_4∶Mn^(2+)的结构、荧光以及长余辉发光性能的影响。Mg离子取代Zn进入Zn_2GeO_4晶格,形成(Zn_(1-x),Mg_x)_2GeO_4固溶体,并产生了晶格畸变。光谱分析结果表明,样品中位于533 nm的绿色荧光源于Mn^(2+)的~4T_1(~4G)→~6A_1(~6S)跃迁。随着Mg离子浓度的增加,(Zn_(1-x),Mg_x)_2GeO_4∶Mn^(2+)样品的激发光谱出现了蓝移现象,说明Mg离子进入到Zn_2GeO_4晶格中对其晶格结构产生了影响,导致(Zn_(1-x),Mg_x)_2GeO_4的带宽发生改变。发射光谱则表明Mg离子进入Zn_2GeO_4晶格引起Mn^(2+)的~4T_1(~4G)→~6A_1(~6S)跃迁绿色荧光发光强度的增强。Zn_2GeO_4基质中的氧空位缺陷陷阱深度由于基质带宽的变化而变深,样品具有良好的长余辉发光效果。通过热释光谱分析研究了材料中缺陷陷阱的特征,进一步证实了(Zn_(1-x),Mg_x)_2GeO_4中缺陷陷阱深度发生改变。根据光谱分析结果给出了(Zn_(1-x),Mg_x)_2GeO_4∶Mn^(2+)中荧光与余辉发光的产生机理。

（Zn1-x,Mgx）2GeO4∶Mn^2＋（ 0≤x≤0. 25） green phosphors were synthesized by the conventional solid-state reaction,and the effect of Mg incorporation on photoluminescence（ PL） and long-lasting phosphorescence（ LLP） characteristics of Zn2GeO4∶Mn^2＋ was systematically studied.The emission spectrum shows a broad emission band centered at 533 nm,which can be assigned to the ^4T1（^4G） →^6A1（^6S） transitions of Mn^2＋ ion. The emission intensity can be increased by the resonant transfer from a subbandgap state in the host to Mn^2＋,and the PLE spectra of（Zn1-x,Mgx）2GeO4∶Mn^2＋ exhibit a blue shift with the increasing of Mg concentration. Thermoluminescence（ TL） spectra indicate that the introduction of Mg into the host deepened the Vo traps,resulting inthe enhanced phosphorescence of Mn^2＋. The possible mechanism of the PL and LLP was discussed based on the PL and TL results.