Abstract:

The spinel?phase Zn₂Ga_2.98-x Ge_0.75O₈:Cr_0.02, La _x (x=0.005,0.010,0.015,0.020,0.025) nanoparticles were synthesized by a hydrothermal method in combination with a subsequent heat treatment. With the La³⁺ doping concentration increasing from 0 to 0.025, the average particle size of these nanoparticls increased from 64 nm to 78 nm. Under 590 nm excitation, La³⁺?doped ZGGO nanoparticles exhibited stronger narrow?band NIR emission peaked at 697 nm, originating from the ²E(²G)→⁴A₂(⁴F) transition of Cr³⁺. From the TEM and emission spectral analyses, it can be found that the increased NIR persistent luminescence is attributed to the increased particle size and the increased number of luminescent centers in a relatively strong crystal field environment. On the basis of thermoluminescence spectra and the afterglow decay curves, it can be found that La³⁺ doping leads to the formation of more traps related to the thermal activation process and the afterglow time exceeding 15 h.

Key words: Persistent luminescence, Cr ion, Photoluminescence, Thermoluminescence

摘要：

采用水热合成法结合800 ℃真空热处理手段，制备了尖晶石相的不同La³⁺掺杂量的近红外长余辉发光纳米粒子Zn₂Ga_2.98-x Ge_0.75O₈:Cr_0.02, La _x （x=0，0.005，0.010，0.015，0.020，0.025）；通过透射电镜和发射光谱分析、热释发光测试手段，研究了La³⁺掺杂对粒子尺寸、有效陷阱的数量及深度、长余辉发光性能的影响。结果表明，当La³⁺掺杂量从0增加到0.025时，粒子尺寸从64 nm增至78 nm；在590 nm光激发下，La³⁺掺杂后ZGGO:Cr³⁺纳米粒子表现出较强的来源于Cr³⁺的²E（²G）→⁴A₂（⁴F）跃迁的697 nm附近的窄带近红外发射；近红外发光的增强归因于粒子尺寸的增加和同时处于较强晶体场环境下的发光中心数目的增多；La³⁺掺杂导致了更多有效陷阱的形成，从而使余辉发光时间超过15 h。

关键词: 长余辉发光, 铬离子, 光致发光, 热释发光