中文摘要：

采用下降法生长技术，沿a向[1120]生长的掺碳钛宝石晶体，在切割等加工过程中掺碳钛宝石晶体经常发生定向开裂的现象．本文对掺碳钛宝石晶体的定向开裂特征和机理进行了分析与研究，发现定向裂纹是在基质氧化铝晶格的（1100）面上发源，并且沿着f00011晶向即c轴方向扩展．采用晶体结构可视化软件（Crystalmaker）模拟得出，基质氧化铝晶格原子在（1100）面上的原子排列最为稀疏，并且在（1100）晶面上，垂直[0001]晶向相邻原子间距最大，在应力作用下晶格（1100）[0001]系统的开裂强度最低．采用光学显微镜、扫描电镜（SEM）和电子探针等仪器和手段，发现在开裂的掺碳钛宝石晶体中沉积了不规则的碳包裹物，降温过程中包裹物的热膨胀失配引起巨大的内应力，使得裂纹在晶体最薄弱的系统（1100）[0001]面上发源并扩展，导致晶体的宏观定向开裂．该研究对优质钛宝石晶体的生长具有重要的理论和现实意义．

英文摘要：

Directional cracking in Ti,C：sapphire crystals grown along [11 - 20] by Vertical Bridgman method often occurs in the cutting and processing process. In this work, we discuss the characteristic and mechanism of directional cracking of Ti,C：sapphire, and find that directional cracking originates from （-1100） lattice plane and spreads along [0001] orientation. Through the Crystalmaker Simulation software, we find that atomic arrangement on （-1100） lattice plane is the most sparse and adjacent atomic spacing is the largest along vertical [0001] direction, so in the system （-1100） [0001] of lattice has a minimum cracking strength, Irregular carbon inclusions in the cracked Ti,C：sapphire are observed with optical microscopy, scanning electron microscopy （SEM）, and X-ray diffractometry. These inclusions cause great internal stress in the cooling process due to thermal expansion mismatch and cracking originating from and spreading in the weak system （1100） [0001] of lattice. As a consequence, macroscopic directional cracking is observed in the Ti,C：sapphire. The study has important theoretical and practical significance for growing high-quality Ti,C：sapphire crystal.