Open AccessMechanism of directional cracking of Ti,C:sapphire crystal
Author(s) -
Keyan Hu,
Jun Xu,
Tang Hui-Li,
Hongjun Liu,
Yongqiang Zou,
Su Liang-Bi,
Weichao Chen,
Zhang Bao-Hui,
Qiuhong Yang
Publication year - 2012
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.61.244210
Subject(s) - sapphire , materials science , cracking , lattice (music) , scanning electron microscope , crystal (programming language) , composite material , crystal structure , crystallography , optics , chemistry , laser , physics , computer science , programming language , acoustics
Directional cracking in Ti,C:sapphire crystals grown along [1120] 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.