晶体生长的边界层效应—兼论光学实时观察法晶体生长技术  

Boundary Layer Effect in Crystal Growth-Comments on the Optical in Situ Observation Technique for Melt Crystal Growth

作　　者：金蔚青[1] 潘志雷[1] 程宁[1] 袁晖[1] 

机构地区：[1]中国科学院上海硅酸盐研究所,上海200050

出　　处：《无机材料学报》1997年第3期279-285,共7页Journal of Inorganic Materials

基　　金：国家科学技术委员会攀登计划资助;国家自然科学基金!59372079

摘　　要：晶体生长边界层模型起源于流体动力学边界层模型，但两者又不完全相同．晶体生长边界层模型有两方面的含义：（1）在固-液界面处的、垂直于界面的、由杂质和组份构成的质量流决定晶体生长速度；（2）在界面附加溶液一侧的质量浓度流，其浓度分布是决定界面稳定性的基本参数．特征扩散长度是表征垂直于界面的质量流的一个重要参数．对熔体晶体生长而言，理论估计此值在0．04～0．4cm之间．光学实时观察法晶体生长技术是一种研究晶体生长过程的新颖方法．它能有效地区分扩散-平流和扩散-对流两种不同的生长状态，其实验测得的KNbO3熔体生长的特征扩散长度值为0．01～0．1cm之间．应用此方法实时观察到胞状结构的形成和发展，也证实了界面附近的质量浓度流是决定界面稳定性的一个重要参数．The model of boundary layer in crystal growth stems from the term boundary layer in fluiddynamics. But they are not the same. As crystal growers we are actually concerned with two(coupled) aspects of the melt-to-crystal transport: (1) with the mass flux across an interface,which we will call the interfacial flux and which determines the crystal growth rate; and (2) withthe concentration profile of growth species in the melt adjacent to the crystal, which is an essentialparameter in morphological stability.Characteristic diffusion distance is an important factor to discuss the mass flux normal tothe interface. For melt growth, the theoretical values range from 0.04~0.4cm. The optical in-situobservation method has been newly developed. The method aims at observing and recording thewhole process of growing and. melting of chide crystals in high temperature up to 1400℃, withvery high visibility of surface kinetic processes and mass flow behaviors near the growing interface.It is measured that during KNbO3 melt growth the values of characteristic diffusion distances arebetween 0.01~0.1 cm of different KNbO3 crystal growth rates. The formation and development ofcellular interface structure are also visualized by means of this method. The result shows that themicro concentration flow near the interface is an essential parameter in morphological stability.

关 键 词：边界层效应 晶体生长 光学实时观察法 结构 晶体 

分 类 号：O766[理学—晶体学] O781