大尺寸晶体快速生长理论与技术的研究进展

“如何突破大尺寸晶体材料的制备理论和技术”是中国科协发布的2021年度的十大前沿科学问题之一,揭示晶体生长机制和突破生长关键技术是大尺寸功能晶体发展的两个趋势。在原子分子尺度上,晶体生长可以是有势垒的热激活过程,也可以是无势垒的超快结晶过程,这与具体的体系以及晶面有关。从界面属性角度来看,光滑界面是以台阶拓展的方式生长;粗糙界面没有明显的固-液分层,通过局部原子固化进行生长。本文从晶体生长理论模型、生长技术及其应用实例,以及分子动力学方法在晶体生长中的应用等方面探讨了近些年大尺寸晶体快速生长理论和技术的研究进展。目前有多种方法制备大尺寸晶体,但普遍存在制备的晶体质量差和性能不稳定等问题。需要突破对晶体生长微观机制上的认识,建立机制与温度、流速等外界因素的内在联系。而利用机器学习力场以及分子动力学模拟方法,建立固-液界面,模拟晶体生长,将是探究晶体生长微观机制的一种有效方式。

Advance in Theory and Technology of Rapid Growth of Large-Size Crystals

“How to break through the preparation theory and technology of large-size crystal materials” is one of the top ten frontier scientific questions released by China Association forScience and Technology in 2021, which revealing the crystal growth mechanism and breaking through the key growth technologies are the two trends of the development of large-size functional crystals. At the atomic or molecular scale, the crysttal growth can be described as a themal activation process with a barrier or an ultrafast growth of crystal without barrier, whiech is related to the specific system and growth direction. Based on the properties of interface, the smooth interface grow by the wray of step expansion, and the rough interface has no obvious solid-liquid stratification, and the growth can be completed bylocal atomic solidification. The advances of growth theory and technology for the large-size crystals in recent years have been summarized from three aspects: model, technology of growth and its application, and the application of molecular dynamics inn crystal growth. At present, there are many methods to grow large-size crystals,but the crystal quality is poor and performance is unstable. The reasons are that the existing technology do not take the micro-mechanism of crystal growth into consideratioln, and the relationship among crystal growth mechanisms and external factors such as temperature and flow rate are not clear. Using machine learning force field and molecular dynamics simulation method to establish solid-liquid interface and to ssimulate crystal growth would be an effective way to explore the micro-mechanism of crystal growth.