人工水晶-x面上巴西双晶的形成机制

本文以人工水晶-x面上的巴西双晶作为研究对象,在实验的基础上,利用X射线衍射形貌术和电子探针显微分析等手段,研究了双晶的形成机制,同时分析了Kern的双晶成核动力学理论的不足之处。作者提出了双晶界应变能势垒的概念,认为由于晶体的不完整性提高了晶体本身的能量状态,结果相对降低了应变能势垒的高度,使得双晶易于发生。本文结合晶体生长实验和晶体缺陷的测试,分析了双晶形成与籽晶取向、杂质、晶体缺陷的相互关系,着重指出缺陷对双晶形成的影响。本文还以凹入角生长机制讨论了双晶的发育。关键词：

THE FORMATION MECHANISM OF THE BRAZIL TWIN ON-x PLANE OF SYNTHETIC QUARTZ

Based on the experiments about the Brazil twin appearing on -x plane {1120} of synthetic quartz, we have studied the formation mechanism of twinning by means of X-ray topography and electron probe micro-analysis and discussed the disadvantage in Kern's theory of nueleation dynemics of twinning. The new concept of strain barrier in twin boundary (SBTB) is proposed and it is considered that the crystal imperfection raises the energy state of the crystal itself and results in the decrease of height of strain barrier and easy formation of twin. We have also discussed the correlation of twinning with seed orientation, impurities and crystal defects in the light of crystal growth experiments and testing of crystal defects, and emphasized the influence of defects on twinning. Finally, the development of twin has been analysed from the view point of re-entrant corner growth mechanism.