Dynamic relaxation process of a 3D super crystal structure in a Cu:KTN crystal

In this Letter,we report the existence and relaxation properties of a critical phenomenon on called a 3D super crystal that emerges at T=TC?3.5℃,that is,in the proximity of the Curie temperature of a Cu:KTN sample.The dynamics processes of a 3D super crystal manifest in its formation containing polarized nanometric regions and/or polarized clusters.However,with strong coupling and interaction of microcomponents,the characteristic relaxation time measured by dynamic light scattering demonstrates a fully new relaxation mechanism with a much longer relaxation time.As the relaxation mechanism of a relaxator is so-far undetermined,this research provides a novel perspective.These results can help structure a fundamental theory of ferroelectric relaxation.     

钽铌酸钾晶体二次电光效应的应用研究进展

钽铌酸钾晶体(KTN)是目前已知的具有最大二次电光系数的晶体,利用其电光效应可改变光的相位、强度和传播方向,可广泛应用于光通讯、屏幕显示和生物医疗等领域。讨论了晶体组分、温度、缺陷和生长条纹对KTN晶体二次电光系数的影响;介绍了近几年国际上报道的几种基于KTN晶体二次电光效应的器件电光调制器、光开关、光束扫描器、变焦透镜和光谱仪,阐述了它们的的基本原理、研究现状和应用前景;对国内外KTN晶体电光器件研究的发展趋势进行了展望。     

基于新型阈值选择方法的变电站红外图像分割

为增强电气设备红外热图像的视觉效果,对其运行状态进行准确检测,提出了一种新型阈值选择的图像分割方法。该方法首先对原始图像进行傅里叶滤波处理形成自动梯度图形,然后针对每种特定类型的目标图像,拟合具有N个相邻点的线性模型计算斜率差的变化趋势,在斜率差分布谷值中挑选适合不同类型故障区域的最佳阈值,最后通过形态学迭代腐蚀,将目标区域与噪声斑点分开,得到清晰的分割图像。该方法可监测各种类型故障,只需校准参数N和确定分割案例,其余部分自动处理。实验结果显示:该方法对目标区域分割的准确率为82%,误分率为0.0182%。通过使用不同类型的红外热故障图像进行测试对比,验证了所提方法的有效性和通用性。     

提拉法生长晶体的自等径控制

采用JPG技术有限公司所开发的自等径控制程序,利用上称重法实现了晶体生长的自等径控制(ADC).通过对生长曲线PID的具体分析及其他晶体生长相关参数的设置,以铌酸锂晶体为对象,成功实现了按预设程序进行的晶体生长自等径控制.     

Growth Defects in Cubic KTa1-xNbxO3 Crystal

Potassium tantalate niobate （KTa1-xNbxO3, KTN） crystals with different dimensions and quality situations were grown by Czochralski method. Crystal growth process and morphology properties of KTN are presented in this paper. It was found that some defects, such as bubble, inclusion, crack, dislocation etc., can all appear if the crystal is grown in an improper condition. The character and formation mechanism of such defects in macro growth are discussed. We consider that the CO2, which was not released absolutely during the sintering process and dissolved in the melt, led to bubbles. The composition of the inclusion caused by high pulling and rotation rates is KTN polycrystalline. The crack and dislocation in KTN crystal mainly come from improper temperature field. Etching and high-resolution X-ray diffraction （HRXRD） experiment results indicate that the central area is the defects concentrated.