In^3+,Si^4+共掺杂ZnBi(0.02)Ga(1.98)O4:Cr^3+的发光与长余辉性能研究

Luminescence and Long Afterglow Properties of In^3+and Si^4+Co-Doped ZnBi0.02 Ga1.98O4∶Cr^3+

长余辉材料在生物医学、信息存储等领域有着广阔的应用前景。人们已在不同体系的材料中成功制备蓝、绿、黄光长余辉材料,且一些材料的高效长余辉性能已能满足实际应用的要求。然而,红色长余辉材料在发光亮度和余辉时间方面都还不够理想。采用高温固相法,通过In^3+, Si^4+共掺杂的方式,制备了深红色发光的Zn(Bi)Ga2O4:Cr^3+材料,并系统地研究了所制备材料的发光光谱、长余辉及热释光性能。XRD分析发现, In^3+, Si^4+参与固相反应并占据了Zn(Bi)Ga2O4适当的晶格位置, In^3+, Si^4+的掺入也不会改变基质的基本相结构。通过监测λ=695 nm的光发射测量了Zn(Bi)Ga2O4:1%Cr^3+;Zn(Bi)Ga2O4:1%Cr^3+, 9%In^3+和Zn(Bi)Ga2O4:1%Cr^3+, 9%In^3+, 7%Si^4+的激发光谱, In^3+, Si^4+的引入改变了Cr^3+的局域环境,从而使得O^2-的2p轨道到Ga^3+的4s4p轨道的电荷迁移带产生红移,并使得Cr^3+的4A^2-4T^1和4A^2-4T^2跃迁强度明显增强。研究440 nm氙灯光激发下发射光谱发现, In^3+的引入改变了部分八面体中Cr^3+的配位环境,造成不同格位的发射峰位置不同,从而使发光光谱表现出非均匀加宽。In^3+掺杂对Cr^3+的配位环境的改变也同时提高了样品的发射光强度。而In^3+, Si^4+共掺杂则使得样品的发射光谱的非均匀加宽效应进一步加强,同时进一步增强了其发光强度。实验表明, 9%In^3+, 7%Si^4+共掺杂的Zn(Bi)Ga2O4:Cr^3+样品表现出最好的光致发光特性。余辉衰减曲线测试发现, In^3+的引入可以大大提高样品的余辉亮度,并延长余辉时间。而Si^4+的引入则进一步的改善了样品的余辉亮度,延长了余辉时间。热释光测试表明, In^3+的引入能提高样品中陷阱能级的深度,而合适浓度的In^3+, Si^4+共掺杂不仅提高了陷阱的深度,也增加了样品中陷阱的浓度。研究发现, 9%In^3+, 3%Si^4+共掺杂的Zn(Bi)Ga2O4:Cr^3+样品具有最好的长余辉性能。相关研究为进一步优化镓酸盐长余辉性材料提供了有意义的参考。

Long afterglow materials have broad application prospects in biomedicine,information storage and so on.Materials with blue,green and yellow afterglow in different systems have successfully prepared,and some of them with good long afterglow properties have met the requirements of practical applications.However,the red long afterglow materials are not ideal in terms of their luminosity and afterglow time.In this paper,In 3+and Si 4+co-doped Zn(Bi)Ga 2O 4∶Cr 3+materials with deep red light luminescence were prepared by high temperature solid-state reaction through.The properties of the luminescent spectra,long afterglow and thermoluminescence of the as-prepared materials were systematically studied.XRD shows that In 3+and Si 4+ions participate in the solid state reaction and occupy the appropriate lattice position of Zn(Bi)Ga 2O 4,and the co-doped In 3+and Si^4+ions have not changed the structure of the host of ZnGa 2O 4.The excitation spectra of Zn(Bi)Ga 2O 4∶1%Cr^3+;Zn(Bi)Ga 2O 4∶1%Cr^3+,9%In^3+and Zn(Bi)Ga 2O 4∶1%Cr^3+,9%In^3+,7%Si^4+have been measured by monitoring emission wavelength at 687 nm.The co-doped In 3+and Si^4+ions change the local environment of Cr^3+,thereby causing the red-shift of the excitation band corresponding to the charge transfer from the 2 p orbital of O 2-to the 4s4p orbital of Ga^3+.Meanwhile,the strength of the 4A 2-4T 1 and 4A 2-4T 2 transitions of Cr^3+is also significantly enhanced by the In 3+and Si^4+co-doped.From the emission spectra excited by the 440 nm light of xenon lamp,it is found that the introduction of In^3+ions changes the local environment of some Cr^3+ions in octahedrons,results in the different emission peak positions of Cr^3+in different lattice sites.This leads to the inhomogeneous broadening of the luminescence spectra in the In^3+doped samples.At the same time,the change of the local environment of Cr 3+ions caused by In^3+doping also improves the emission intensity of the samples.The In^3+and Si^4+co-doping further enhances the inhomogeneous broadening of the emission spectra and the luminescence intensity is also intensified.It is found that Zn(Bi)Ga 2O 4∶Cr^3+co-doped with 9%In^3+,7%Si^4+presents the best photoluminescence properties in our experiment.Based on the measured afterglow decay curves,it is found that the introduction of In 3+can greatly improve the afterglow brightness of the sample and prolong the afterglow time.Moreover,the further introduced Si^4+ions can ulteriorly improve the afterglow brightness and prolong the afterglow time.Thermoluminescence tests show that the introduction of In^3+ions can increase the depth of trap levels in the sample,while the co-doped In^3+,Si^4+ions with appropriate concentrations not only increase the depth of the trap but also enhance the concentration of traps in the sample.The investigation in the present work proves that Zn(Bi)Ga 2O 4∶Cr^3+co-doped with 9%In^3+,3%Si 4+have the best long afterglow properties.Related studies provide a meaningful reference for further optimization of long afterglow gallate materials.