相变温度附近钽铌酸钾晶体的电光响应研究

发布时间：2018-03-07 17:24

本文选题：钽铌酸钾晶体　切入点：电光效应　出处：《哈尔滨工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：钽铌酸钾晶体KTa_(1-x)Nb_xO_3(KTN)由于其在居里温度附近具有很优异的二次电光效应而被广泛地研究和应用,被认为是一种制备光学器件的优异电光材料。对于KTN晶体在相界附近优异电光性能的起源,目前广泛认为是由于相变过程中晶体内部铁电畴的影响。但对于KTN晶体中铁电畴的观察和其影响电光效应的机理却鲜有研究。本文主要研究了KTN晶体的电光性能对温度与电场强度的动态响应特性,分析铁电畴在相变温度附近的演化过程,及其影响电光效应的机理。研究了KTN晶体的基本物理性质。采用电桥法测量了KTN晶体相对介电常数的温度特性曲线,由介电反常现象确定其居里温度,从而得到了晶体的组分。由介电常数偏离居里外斯定律出发,计算KTN晶体的弛豫因子,发现其在居里温度附近具有一定的弛豫性,从侧面验证在此特征温度范围内铁电畴的存在。测量了晶体的电滞回线,得到了矫顽场、自发极化强度等特征参量值,为极化处理和电光实验过程中外加电压的范围提供理论依据。研究了KTN晶体铁电畴对温度的动态响应。搭建Senamont单光束补偿系统对极化完整的KTN晶体在升温过程中的线性、二次电光系数进行测量。将时域输出电压信号波进行傅里叶变换,得到频域信号波,分析居里温度附近的电光效应。利用偏光显微镜对钽铌酸钾晶体的铁电畴进行了直接观测。对比晶体极化处理前后、温度升高和降低过程中晶体的偏光性,分析铁电畴随温度的演化过程。研究了相界附近KTN晶体的铁电畴对外加电场的动态响应。采用单光束补偿法测量了相变附近晶体的电光系数随电场强度的变化规律。设计实验并测量了在变化的交流电场下、变化的直流电场下的线性、二次电光系数,并将极化前后的结果、不同温度条件下的结果分别进行对比。由唯象的朗道理论分析解释了极化处理对铁电畴的诱导取向和束缚效应,外加直流电场的场强和方向对晶体铁电畴重取向模式影响,揭示电光效应的动态响应机制。
[Abstract]:The potassium tantalum niobate crystal KTaS _ 1-x _ X _ _ _. It is considered to be an excellent electro-optic material for the fabrication of optical devices. For the origin of the excellent electro-optic properties near the phase boundary of KTN crystal, At present, it is widely believed that the effect of ferroelectric domain in crystal is due to the influence of ferroelectric domain in the process of phase transformation. However, the observation of ferroelectric domain in KTN crystal and the mechanism of its influence on electro-optic effect are seldom studied. The electro-optic properties of KTN crystal are mainly studied in this paper. Dynamic response to temperature and electric field strength, The evolution process of ferroelectric domain near phase transition temperature and the mechanism of its influence on electro-optic effect are analyzed. The basic physical properties of KTN crystal are studied. The temperature characteristic curve of relative dielectric constant of KTN crystal is measured by bridge method. The Curie temperature of KTN crystal is determined by dielectric anomaly, and the composition of the crystal is obtained. The relaxation factor of KTN crystal is calculated from the deviation of dielectric constant from Curie's law, and it is found that it has certain relaxation property near Curie temperature. The existence of ferroelectric domains in this characteristic temperature range is verified from the side. The hysteresis loops of the crystals are measured, and the coercive field, spontaneous polarization intensity and other characteristic parameters are obtained. This paper provides a theoretical basis for the range of applied voltage in polarization processing and electro-optic experiments. The dynamic response of ferroelectric domains to temperature in KTN crystal is studied. The linearity of Senamont single-beam compensation system for polarized KTN crystals during heating process is built. The secondary electro-optic coefficient is measured. The time-domain output voltage signal wave is transformed by Fourier transform, and the frequency-domain signal wave is obtained. The electrooptic effect near Curie temperature is analyzed. The ferroelectric domain of potassium tantalum niobate crystal is observed directly by polarizing microscope. The evolution process of ferroelectric domain with temperature is analyzed. The dynamic response of ferroelectric domain of KTN crystal near phase boundary to external electric field is studied. The variation of electro-optic coefficient with electric field intensity is measured by single beam compensation method. Have been designed and measured in a variable alternating current field, The variation of the linear, secondary electro-optic coefficients under the DC field, and the results before and after polarization, The results are compared at different temperatures. The induced orientation and binding effect of polarization treatment on ferroelectric domains are analyzed and explained by phenomenological Landau theory, and the effect of the field strength and direction of the applied DC field on the reorientation mode of ferroelectric domains is explained. The dynamic response mechanism of electro-optic effect is revealed.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O614.113;O73

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