铌酸锂晶体缺陷研究中的介尺度团簇演变

Evolution of Mesoscale Clusters in Study of Defects in Lithium Niobate Crystals

铌酸锂晶体中存在着丰富的缺陷结构,主要包括VLi、NbLi^(4+)、V_(Nb)以及VO等点缺陷。缺陷的存在会在很大程度上影响铌酸锂晶体的性质,如压电、电光、铁电、光折变、非线性光学性质以及激光损伤阈值,进而影响声表面波、电光调制器、声光调制器、温度/压力/加速度传感器等器件性能。铌酸锂晶体中缺陷形成的主要过程可以归结为以O2–为中心的介尺度团簇演变。明确铌酸锂晶体缺陷形成过程中的介尺度团簇演变机制对于缺陷的控制具有十分重要的意义。本文将从缺陷类型、形成能以及介尺度团簇模型研究铌酸锂晶体中缺陷的动态演变过程以及形成机制。最后分析铌酸锂晶体结构中缺陷导致的杂化、再杂化过程,同时考虑多种自由度的耦合,为铌酸锂晶体的缺陷控制、快速生长以及性能调控贡献力量。最后举例介绍分析铌酸锂晶体缺陷与性质、功能的关联关系。

There are abundant defect structures in lithium niobate crystals,mainly including VLi,NbLi^(4+),Vnb and Vo point defects.The existence of defects greatly affects the properties of lithium niobate crystal(ie.,piezoelectric,electro-optic,ferroelectric,photorefractive,nonlinear optical properties and laser damage threshold)as well as the performance of SAW,electro-optic modulator,acousto-optic modulator,temperature/pressure/acceleration sensor and other devices.The main process of defect formation in lithium niobate crystal can be attributed to the evolution of mesoscale clusters centered on O^(2-)ions.It is thusimportant to understand the evolution mechanism of mesoscale clusters in the defect formation process of lithium niobate crystal for defect control.This paper was to investigate the dynamic evolution process and formation mechanism of defects in lithium niobate crystal from the aspects of defect types,formation energy and mesoscale cluster model.The hybridization and rehybridization process caused by defects in lithium niobate crystal structure was analyzed,and the coupling of multiple degrees of freedom was considered,which contributes to the defect control,rapid growth and performance control of lithium niobate crystal.In addition,the correlation between the defects of lithium niobate crystal and its properties as well asfunctions was also analyzed.