磷酸二氢钾晶体表面点缺陷的理论研究  

Theoretical Study on Point Defects on Surfacesof KH_(2)PO_(4) Crystals

作　　者：赵骁骥 李妍璐[1] 赵显 ZHAO Xiaoji;LI Yanlu;ZHAO Xian(Institute of Crystal Materials and State Key Laboratory of Crystal Materials,Shandong University,Jinan 250100,China;Center for Optics Research and Engineering,Shandong University,Qingdao 266237,Shandong,China)

机构地区：[1]山东大学晶体材料研究院,晶体材料国家重点实验室,济南250100 [2]山东大学光学高等研究中心,山东青岛266237

出　　处：《硅酸盐学报》2023年第6期1412-1424,共13页Journal of The Chinese Ceramic Society

基　　金：山东省自然科学基金重大基础研究项目(ZR2020ZD35);山东大学“青年学者未来计划”(2018WLJH65);山东大学晶体材料国家重点实验室青年人才培育课题。

摘　　要：磷酸二氢钾(KH_(2)PO_(4),KDP)晶体是目前唯一可在惯性约束核聚变装置中得到实际应用的非线性光学材料。由于晶体缺陷大大降低了非线性光吸收、激光损伤阈值等光学性能,因此,探明KDP晶体缺陷对其电子结构和光学性质的影响机制对于提升其光学性能具有重要意义。本工作采用第一性原理方法计算了KDP晶体(100)和(101)表面上氢空位和氧空位缺陷的结构、稳定性及电子结构特征,研究了酸环境对表面空位缺陷结构及电子结构的影响规律及微观机制。结果表明:氢空位和氧空位缺陷在KDP晶体(100)和(101)表面上均比在晶体中更容易形成。(100)表面对氢空位及氧空位均具有较高的容忍性,然而,(101)表面的氧空位极易失去电子,在带隙中引入缺陷能级,从而引起额外光吸收,对晶体光学性质产生不利影响。酸性环境会导致(100)表面产生更多氧空位,并诱导产生氧空位缺陷能级;同时,酸性环境有利于修复表面氢空位,并消除氧空位在(101)表面电子结构中引入的缺陷态,有利于提升晶体(101)表面质量及光学质量。KDP crystal is a nonlinear optical material that is used in inertial confinement nuclear fusion devices.However,the defects seriously reduce the optical performance such as light absorption and laser damage threshold of KDP crystals.It is thus of great significance to investigate the influence mechanism of KDP crystal defects on its electronic structure and optical properties for the improvement of its optical properties.In this paper,the structure,stability and electronic structure of hydrogen and oxygen vacancy defects(i.e.,V and Vo)on the growth surfaces(100)and(101)of KDP crystals were investigated by using the first-principle calculation.The effect and microscopic mechanism of acidic environment on the structure and properties of surface defects were also discussed.The results indicate that the Vh and Vo defects both are easier to be formed on the surfaces(100)and(101)rather than in bulk KDP crystal.The surface(100)has an intense tolerance for surface Vh and Vo defects,while Vo on the surface(101)prefers to lose electrons,and introduces a deep defect level in the band gap,thusdamagingthe optical properties of the KDP crystal.In addition,acidic environment canlead to more Vo defects on the surface(100)and introduce the defect level in the band gap.Also,acidic environment is conducive to the repair of the Vh defects on the surfaces,and can eliminate the defect states introduced by the surface Vo defects on the surface(101),which is conducive to improving the quality and optical quality of the crystal surfaces.

关 键 词：第一性原理 磷酸二氢钾 表面 缺陷 

分 类 号：O77[理学—晶体学]