[论文解读] Luminescence of alpha-quartz

A.N. Trukhin, Kaspars Truhins|arXiv (Cornell University)|Sep 19, 2012

Glass properties and applications参考文献 6被引用 5

一句话总结

本综述总结了过去30年关于α-石英发光特性的研究，重点探讨了在电离辐射下发射于2.6–2.7 eV的自陷激子（STE），其量子产率约为0.2，以及由辐照诱导的缺陷相关发光。主要发现包括：来自AlO4–Me复合物的发光带（低温下为6 eV，高温下为3.4 eV）、与Ge相关的STE发光，以及贵金属掺杂（Cu在3.4 eV，Ag在4.75 eV）的发光，所有这些发光行为在碱金属离子与贵金属离子交换后均可逆。

ABSTRACT

Among the host materials luminescence the luminescence of the self-trapped exciton (STE) is reviewed. This luminescence, which band is situated at 2.6 to 2.7 eV, could be observed mainly under ionising radiation with energetic yield about 0.2. The STE does not participate in pure recombination processes. Host material defect luminescence at 5 eV appears in alpha-quartz after heavy irradiation. It is constituted of permanent defect after neutron irradiation and transient defect after dens electron beam irradiation. This luminescence could be observed well at temperatures below 60 K. All another luminescence are of impurity nature. The Ge impurity luminescence in alpha-quartz explained as STE near Ge. The aluminium and alkali complexes. One of them is with UV band at 6 eV, appears at low temperatures and could be excited only in tunnelling recombination process between pairs (AlO4 Me), where Me is an alkali ion captured an electron and a hole remains on aluminium tetrahedron. Another luminescence with band at 3.4 eV is also luminescence of complexes (AlO4 Me), which behaviour is similar to the luminescence of alkali alumosilicate glass. The third luminescence with band at 3 eV could be observed mainly in natural alpha-quartz, bright at temperatures below 200 K and is interpreted as STE like luminescence at alumosilicate clasters. The exchange of alkali ions to noble ions of copper of silver reduces original luminescence of alumo alkali complexes and luminescence of noble ions appears. The main band of copper related luminescence is at 3.4 eV and that of silver is at 4.75 eV, both could be observed up to 500 K. their nature could be well described in terms of intraions transition. Exchange of noble ions back to alkali ions renews initial luminescence of the samples.

研究动机与目标

• 系统综述过去三十年中α-石英的发光特性研究。
• 识别并表征各种发光带的来源，包括自陷激子和缺陷相关发光。
• 阐明杂质（Ge、Al、碱金属、Cu、Ag）在不同辐照和温度条件下对发光行为的影响。
• 解释在碱金属离子与贵金属离子交换后，发光变化的可逆性。

提出的方法

• 分析数十年来天然和辐照α-石英样品的发光光谱实验数据。
• 利用温度依赖性发光测量以区分瞬态缺陷与永久缺陷。
• 应用隧穿复合模型以解释AlO4–Me复合物中的激发机制。
• 比较合成与天然石英的发光行为，以识别本征发光与杂质相关发光。
• 通过离子交换实验研究碱金属离子被Cu或Ag取代后发光变化的可逆性。
• 将发射带与特定缺陷结构（如(AlO4Me)、与Ge相关的中心、贵金属离子态）相关联。

实验结果

研究问题

• RQ1 α-石英中2.6–2.7 eV发光带的成因是什么？为何其与自陷激子相关？
• RQ2 中子辐照与电子束辐照如何不同地影响α-石英中的缺陷相关发光？
• RQ3 在低温下AlO4–Me复合物中观测到的6 eV发光带的起源是什么？
• RQ4 Cu和Ag掺杂如何改变α-石英中铝碱复合物的发光特性？
• RQ5 在离子交换后，掺杂α-石英的发光行为在多大程度上可逆？

主要发现

• α-石英中的自陷激子（STE）发光在2.6–2.7 eV之间，且在电离辐射下量子产率约为0.2。
• 重辐照后出现5 eV的缺陷发光带，其来源于中子辐照后的永久缺陷和电子束辐照后的瞬态缺陷，可在60 K以下观测到。
• AlO4–Me复合物中6 eV的发光带源于隧穿复合过程，仅在低温下可观测。
• AlO4–Me复合物在3.4 eV处的发光带与碱金属铝硅酸盐玻璃中的发光相似，且在200 K以下尤为显著。
• 铜掺杂引入主发光带于3.4 eV，银掺杂则产生4.75 eV的发光带，两者在500 K以下均稳定，归因于离子内跃迁。
• 碱金属离子与贵金属离子（Cu、Ag）之间的离子交换可逆地改变发光：用Cu或Ag取代碱金属会淬灭原有复合物的发光，而将离子恢复后可使初始发光重新出现。