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无机材料学报

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近化学计量比LiNbO3晶体电畴结构观察和机理探讨

郑燕青, 陈建军, 路治平, 王绍华, 施尔畏   

  1. 中国科学院上海硅酸盐研究所, 上海 201800
  • 收稿日期:2004-10-15 修回日期:2004-11-11 出版日期:2005-11-20 网络出版日期:2005-11-20

Observation of Ferroelectric Structures of Near-stoichiometric LiNbO3 Crystal and Its Mechanism

ZHENG Yan-Qing, CHEN Jian-Jun, LU Zhi-Ping, WANG Shao-Hua, SHI Er-Wei   

  1. Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 201800, China
  • Received:2004-10-15 Revised:2004-11-11 Published:2005-11-20 Online:2005-11-20

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摘要： 采用双坩埚提拉法(DCCZ)生长了各种不同成分的近化学计量比LiNbO3晶体, 并用腐蚀法观察了其电畴结构. 结果表明, 化学成分对未经极化处理晶体的电畴结构起决定性作用, 当Li2O
含量处于49.4mol%附近时, 晶体z面电畴呈现特殊的三次对称反畴; 当晶体中Li2O含量为49.7mol%时, 晶体为完全单畴. 本文对其形成机理进行了探讨, 认为在由顺电相向铁电相转变
时, 局部铁电畴的极性方向与该处沿z轴方向的温度梯度正负密切相关, z轴生长晶体时, 由于相变发生所处位置离生长界面的距离受LiNbO3晶体计量比影响, 所处温场固有温梯也
随之不同, 在此基础上解释了不同成分晶体的电畴结构形成原因. 最后讨论了控制铁电畴结构的工艺措施.

关键词: LiNbO3晶体, 化学计量比, 电畴结构, 机理

Abstract: Near stoichiometric LiNbO3 crystals of varied composition were grown by a double crucible Czochralski method. An etching method was applied to observe the ferroelectric domain structures
of the as-grown crystals. The results show that the congruent crystal grown along z-axis contains a domain structure consisting of concentric rings. The crystal with composition of 49.4mol% Li2O
contains a special domain structure consisting of three fan-shape opposite domains with three-fold symmetry, which is consistent with the symmetry of the crystal structure. The crystal with composition
of 49.7mol% Li2O has a single domain structure. The formation mechanism of the domain structures was discussed based on a thermoelectric field model. It is argued that the sign of the temperature
gradient along z-axis in the front of para- ferroelectric interface is the critical factor that determines the polarity direction of the domain in development. Finally, the technological methods to control the domain structures were discussed.

Key words: LiNbO3 crystal, stoichiometry, ferroelectric domain structure, mechanism

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