摘要
在局域密度近似下,采用第一性原理方法系统地研究了高压对LaBr3晶体结构、电子结构与光学性质的影响。计算的晶格参数和体弹模量均与报道的实验结果吻合。能带结构计算表明,无压强作用时LaBr3为直隙绝缘体,其价带和导带分别主要由Br 4p态和La 5d态电子构成;施加压强后,其逐渐转变为间隙绝缘体,且带隙随压强增大而线性减小。分析光学性质发现在可见光和红外区域LaBr3的透射率均达到80%,表明其为理想透明闪烁材料。随着压强的增大,介电函数虚部两个峰值较高的峰位、光学吸收边及透射边均发生红移,且静态介电常数、折射率以及反射率均增大。研究表明,高压有效调制了LaBr3的电子结构和光学性质,计算结果为LaBr3光电材料的设计与应用提供了理论依据。
Crystal structure and electronic and optical properties of LaBr3 under high pressure are systematically investigated by first-principles method within the local-density approximation （LDA）. The calculated lattice parameters and bulk modulus are in good agreement with the experimental data reported. The results of the band structure calculation show that LaBr3 is a direct-band-gap insulator without pressure, and the top of the valence band is mainly composed of Br 4p states while the lower part of the conduction band is dominated by the La 5d states. Under high pressure, LaBr3 gradually transforms into an indirect-band-gap insulator while the band gap presents a basically linear reduction trend with the increase of pressure. Analysis of the optical properties shows that the transmittance of LaBr3 reaches 80% in the visible and infrared region, indicating that LaBr3 is an ideal transparent material. With the increase of pressure, two higher peaks of the imaginary part of the dielectric function, the optical absorption edge and the optical transmittance edge are red-shifted. Furthermore, the static dielectric constant, the refractive index and the reflectivity of LaBr3 increase gradually. In a word, the involved results show that the high pressure effectively modulates the electronic structure and optical properties of LaBr3, which can provide a theoretical basis for the design and application of LaBr3 optoelectronic materials.
出处
《光学学报》
EI
CAS
CSCD
北大核心
2013年第2期143-150,共8页
Acta Optica Sinica
基金
国家自然科学基金(11103089)
江苏省自然科学基金(BK2012460)
江苏省高校自然科学研究面上项目(12KJB510011)
江苏高校优势学科建设工程资助课题
关键词
材料
LaBr3
第一性原理
压强
电子结构
光学性质
materials
LaBr3
first principles
pressure
electronic structure
optical property
