Tm³⁺离子掺杂的透明玻璃陶瓷的光谱学研究

【作者】 高当丽；

【导师】 郑海荣；

【作者基本信息】 陕西师范大学 ， 光学， 2008， 硕士

【摘要】 稀土离子掺杂的荧光材料被广泛地应用于灯光照明、平板显示、光学通讯以及制作激光器等领域。晶体和玻璃常常作为稀土离子掺杂的基质材料。作为晶体和玻璃的混合物,稀土掺杂的透明氧氟化物玻璃陶瓷自从被报道之后,吸引了大批学者的研究兴趣。透明氟氧化物玻璃陶瓷不仅具有氟化物晶体良好的光学特性,还具有氧化物玻璃优良的机械和化学稳定性。由于掺杂其中的稀土离子一部分优先富集在纳米晶体里,一部分残留在玻璃基质里,为在同一材料中研究玻璃体和晶体的光谱学性质提供了可能。本论文利用低温激光选择激发技术,选择激发两种局域环境稀土离子,分离了晶相和玻璃相Tm³⁺离子的发射谱,发现玻璃相Tm³⁺离子更有利于上转换,讨论了两种局域环境稀土离子荧光光谱的温度特性并研究了Tm³⁺离子掺杂的透明氟氧化物玻璃陶瓷材料在激光辐照下的热传导效应,全文可分为三个部分:第一部分Tm³⁺掺杂含有LaF₃纳米晶粒玻璃陶瓷的激光选择激发利用低温下的选择激发技术,研究了Tm³⁺离子掺杂的玻璃陶瓷的晶相或玻璃相环境的Tm³⁺离子的光谱特性。两种局域环境Tm³⁺离子的荧光特性的研究结果表明:处于不同环境的Tm³⁺离子荧光光谱可以通过调谐激发波长来分离。激发光源为红色单色激光时,处于玻璃基质中Tm³⁺离子发光中心有利于蓝色上转换发射,当激发波长和激发态吸收一致时,获得了最高的上转换效率;当激发波长和基态吸收一致时,处于LaF₃纳米微晶内的Tm³⁺离子发光中心被选择激发,一步荧光强度最大。第二部分Tm³⁺掺杂的透明氟氧化物玻璃陶瓷荧光光谱的温度特性研究了不同环境和温度条件下Tm³⁺掺杂的透明氟氧化物玻璃陶瓷的选择激发光谱和荧光弛豫性质。在20 K到450 K的温度范围内,探讨了发光离子的局域环境对荧光光谱温度依赖关系的影响。观测结果显示玻璃环境中发光离子的荧光寿命受温度影响较小,而位于晶相环境中离子的荧光寿命则显示较强的温度依赖特性。分析了选择激发条件下³H₄能级荧光寿命随温度变化的规律,并对荧光衰减过程的二阶指数行为进行了讨论。第三部分Tm³⁺离子掺杂的透明纳米玻璃陶瓷的局域热效应研究发光离子在光激发下的光谱性质及动力学过程依赖于发光离子的局域温度,而该局域温度又依赖于样品的环境温度、激发光的强弱、样品的内部结构及其导热性能等。本部分将利用固体中的热传导理论和高分辨激光光谱学方法,对发生在透明氟氧化物纳米玻璃陶瓷中的光致局域热效应进行研究,分析探讨纳米玻璃陶瓷中的热传导性质以及其对掺杂离子的荧光性质的影响。更多还原

【Abstract】 Luminescent materials based on lanthanide ions has been widely used as phosphors in lamps and display,components in optical communication,and active materials in laser devices. Crystalline and amorphous materials are frequently used as matrixes for lanthanide ions.As a mixture of crystal and glass,transparent oxyfluoride glass ceramics doped with lanthanide ions have attracted great attention since it was reported.The excellent combination of optical advantages of crystal host with chemical advantages of oxide glass matrix enhances the application of lanthanide doped optical materials significantly.Because the doped ions distribute both in nanocrystals and in glass matrix,two distinct local environments,crystal phase and glass phase,coexist in glass ceramics.This provides us a unique system for investigating spectral properties of doped ions in different local symmetry under identical conditions.In current paper,fluorescence from the ions in crystal phase and glass phase were investigated with selective excitation for Tm³⁺ doped transparent oxyfluoride glass ceramics containing LaF₃ nanocrytsals,it was found that the glass phase favors the blue up-conversion of Tm³⁺ when a single pulsed red light is applied.It is discussed that the dependency on temperature of fluorescence spectra and spectroscopic study of local thermal effect in transparent glass ceramicses containing nanoparticles.The paper is mostly divided into three parts:Part One:Spectroscopic properties of the ions sited in different local environments have been studied.It was found that the glass phase favors the blue up-conversion of Tm³⁺ when a single pulsed red light is applied.The most efficient up-conversion was obtained when the excited stated absorption is in resonant with excitation light.Ions in crystal phase and in glass phase were excited separately by tuning the excitation wavelength.Part Two:The selective excited spectra of Tm³⁺ doped transparent oxyfluoride glass ceramics at different temperatures were investigated,which shows that the line width,intensity of fluorescence and the spectra position all change with the temperature increasing in the range of 20K to 450K.The dependency on temperature of fluorescence spectra is influenced directly by the local environment. The fluorescence lifetime of active ions in glass phase ambient is less affected,while is largely affected in crystal phase ambient.The rule reliance upon the temperature of ³H₄ lifetime is studied under selective excitation as well as the behavior on the quadric exponential in the process of fluorescence decay.Part Three:Fluorescence dynamics processes depends on the local temperature of optical active ions,which is affected by the excitation laser,sample bath temperature and thermal conductivity of the sample. In this paper,local thermal effect for the fluorescence of triply ioned rare earth ions doped in nanocrystals is studied with laser spectroscopy and thermal conduction theory for transpartent oxyfluoride glass ceramics.更多还原