摘要
为深入地了解纯NaCl本身及其Al和Ca掺杂变体的热释光峰值温度偏移特性,通过第一性原理计算与热释光实验的结合方法,探讨了掺杂如何影响晶体的电子结构,并进一步分析热释光峰值温度的偏移机制.计算结果显示掺杂Al后NaCl的带隙略有增加至5.20 eV,掺杂Ca则导致带隙显著减小至0 eV,这些掺杂不仅改变了带隙宽度,还引入了不同的缺陷形成能,这可能导致热释光峰值温度在较低温度出现,且会随实验条件的变化而偏移.通过热释光实验对理论预测结果进行了验证,结果显示在加热速率增加时,所有样品的热释光峰值温度均有所增加,且NaCl:Al的变化最为显著,从276 K增至340 K;而在1—25 mGy剂量范围内随着辐照剂量的增加,热释光峰值温度的增长变化较小,尤其是NaCl:Ca仅从195 K增至202 K.基于第一性原理的计算及热释光峰值温度偏移特性的实验研究对于不同掺杂材料的应用具有重要参考意义.
To gain a more in-depth understanding of the thermoluminescence peak temperature shift characteristics of pure NaCl itself and its A1 and Ca doped variants,a combination of the first-principles calculations and thermoluminescence experiments is used to explore how doping affects the electronic structure of the crystal and further analyze the mechanism of peak temperature shift in thermoluminescence.The calculations indicate that doping NaCl with Al slightly increases its band gap to 5.20 eV,whereas doping with Ca reduces it dramatically to 0 eV.These changes can modify the band gap width but introduce distinct defect formation energy values.Such changes may cause the thermoluminescence peak temperature to occur at lower temperatures and shift with the change of experimental conditions.The theoretical predictions are validated through thermoluminescence experiments,showing that the thermoluminescence peak temperatures of all samples rise with heating rate increasing.Notably,the change is most significant for NaCl:Al,where the peak temperature rises from 276 to 340 K.Meanwhile,as the irradiation dose increases in a range of 1-25 mGy,the growth of the thermoluminescence peak temperature turns relatively small,especially for NaCl:Ca,the peak temperature rises only from 195 to 202 K.This comprehensive analysis of the electronic structures and defect formation energy provides an insight into the thermoluminescence behavior of NaCl crystal.Doping with Al and Ca introduces mid-gap states that act as traps for charge carriers.These traps play a crucial role in the thermo luminescence process,capturing electrons during irradiation and releasing them upon heating,which leads to the observed luminescence.The presence of these traps and their specific energy levels relative to the conduction and valence bands directly influences the temperature at which the peak luminescence occurs.In addition,this study explores how the changes of electronic structure,caused by doping,affects the recombination process of charge carriers,which is very important for the thermoluminescence phenomenon.It also investigates the influence of external factors,such as the rate of heating and the dose of irradiation,on the stability and shift of thermoluminescence peak temperature.These findings emphasize the complex interactions between material composition,structural defects,and experimental conditions in determining the thermo luminescence characteristics of doped NaCl crystals.The results of this research are of great significance for the application of doped materials in various fields,including radiation dosimetry and solid-state lighting.The ability to manipulate the thermoluminescence peak temperatures through doping opens up new ways for designing materials with tailored luminescence properties for specific applications.This study not only deepens our understanding of the fundamental mechanisms of thermo luminescence but also highlights the potential of firstprinciples calculations combined with experimental analysis in the development of new materials with desired optical and electronic characteristics.
作者
杨俊
赵修良
陈瑞达
侯佳斌
侯玉苗
贺三军
周超
刘丽艳
Yang Jun;Zhao Xiu-Liang;Chen Rui-Da;Hou Jia-Bin;Hou Yu-Miao;He San-Jun;Zhou Chao;Liu Li-Yan(School of Nuclear Science and Technology,University of South China,Hengyang 4211001,China;Key Laboratory of Advanced Nuclear Energy Design and Safety,Ministry of Education,University of South China,Hengyang 421001,China)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2024年第13期309-316,共8页
Acta Physica Sinica
基金
国家自然科学基金(批准号:12005098)
湖南省教育厅科学研究项目(批准号:19A431)资助的课题。
关键词
热释光特性
NaCl掺杂
第一性原理
电子结构
thermoluminescence properties
NaCl doping
first-principles
electronic structure
