对流效应和溶质浓度对KNbO_3晶体界面形貌稳定性的影响  

Effect of Convection and Solute Concentration on the Morphological Instability of KNbO_3 Crystal

作　　者：蔡丽霞[1] 金蔚青[1] 潘志雷[1] 刘照华[1] 梁歆桉[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》2001年第4期609-614,共6页Journal of Inorganic Materials

基　　金：国家科学技术委员会攀登资助项目(95-预-34);国家自然科学基金重点项目(59832080)

摘　　要：研究了在不同对流形态对ＫＮｂＯ３晶体生长形貌的影响．在温度梯度较小的扩散－平 流区域，晶体以枝蔓晶的形态生长；而在温度梯度较大的扩散－对流区域，生长出的晶体呈现 光滑晶面．通过测定不同区域ＫＮｂＯ３晶体界面附近的溶质浓度分布，从对流效应降低晶体界 面附近的溶质浓度分布的不均匀性的角度研究了对流效应对晶体界面形貌稳定性的影响，证明 对流效应提高了晶体界面形貌稳定性，与晶体界面弥散度的理论计算结果相一致．同时解释了 扩散－对流区域的晶体尺寸大于扩散－平流区域的晶体尺寸的原因．观察并定性地解释了不同 溶质浓度ＫＮｂＯ３形成不同的界面非稳定形貌，当 ＫＮｂＯ３重量百分比为２０ｗｔ％时形成骸晶， ３０ｗｔ％时形成枝蔓晶．The effect of diffusive-advection and diffusive-convection on KNbO3 crystal morphologies were studied respectively. Under diffusive-advection environment, the grain grows in dendritic pattern, while, under diffusive-convection, it grows in a pattern that makes the grain surface smooth. Based on the fluid effect on solute concentration distribution near the grain, the influence of fluid effect on morphological stability was analyzed. It is proved that convection can enhance the morphological stability and this result agrees with the DMSI (Diffuseness of the Melt-Solid Interface) theoretical calculation. The reason that the grain size in diffusive-convective area is larger than that in diffusive-advective area was interpreted. Additionally, the solute concentration effect on KNbO3 grain morphologies was also studied qualitatively.

关 键 词：KNBO3 枝蔓晶 界面形貌稳定性 晶体生长 铌酸铅晶体 对流效应 溶质浓度 

分 类 号：O782[理学—晶体学] O614.113