基于相移干涉技术的晶体溶解及生长边界层实时监测

晶体在溶解及生长过程中边界层的信息直接影响晶体生长速度和物质输运过程,进而影响晶体质量和生长机制。本文利用相移干涉技术建立了晶体生长过程实时监测系统,对无机盐晶体溶解及生长过程中的边界层信息及物质输运过程进行了实时监测,获得了整个实验过程中的晶体生长速度。实验表明:在溶解过程中,边界层内浓度分布与晶体界面距离呈指数下降关系,边界层内浓度差与晶体溶解速度随时间呈指数减小关系;在结晶过程中,边界层内浓度分布规律与溶解过程相反;边界层内浓度差和晶体生长速度曲线则呈现出先上升再下降最后趋于稳定的规律,且在重力场和物质输运过程的共同作用下,晶体表面会产生浮力对流现象。

Real-time Monitoring of Boundary Layer Evolution in Crystal Dissolution and Growth Process Based on Phase Shifting Interferometry

Information of boundary layer in process of crystal dissolution and growth directly influences the crystal growth rate and the mass transport process, and then influences the crystal quality and growth mechanism. A real-time monitoring system for crystal grouth process was established, based on phase shifting interferometry. Boundary layer information in process of inorganic salt crystal dissolution and growth and the mass transport process were monitored in real-time, and the crystal growth rate in full experimental process was obtained. Experimental results indicate that during crystal dissolution process, concentration distribution in boundary layer decreased exponentially with the increase of distance to the crystal interface; the concentration difference in boundary layer and crystal dissolution rate decrease exponentially with the time. In the process of crystallization, the relation between concentration distribution in boundary layer and the distance to crystal interface is opposite to that in crystal dissolution process; the evolution of crystal growth rate is similar to concentration difference in boundary layer, that increases first and then decreases, finally tends to be stable. The buoyancy convection occurs on the crystal surface due to the combined action of gravitational field and mass transport.