Mechanism of Surface Cracking in a Ca12Al14O33 Crystal during the Cooling Process

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• 作者：Yanru Yin ; Zhitai Jia ; Wenxiang Mu ; Zeliang Gao ; Jian Zhang ; Xutang Tao
• 刊名：Crystal Growth & Design
• 出版年：2016
• 出版时间：April 6, 2016
• 年：2016
• 卷：16
• 期：4
• 页码：1903-1906
• 全文大小：282K
• ISSN：1528-7505

文摘

Bulk Ca₁₂Al₁₄O₃₃ (C12A7) crystals were successfully grown by the Czochralski (Cz) method. However, the surface exhibited severe cracking to a depth of about 1 mm during cooling of the as-grown crystals to room temperature. To determine the mechanism of the surface cracking we measured powder crystal X-ray diffraction, Raman spectroscopy, thermal gravimetry, and infrared spectroscopy of the OH-stretching band. It was found that the lattice parameters of the cracked crystal surface and the core were different. A weight increase in the TGA curve was observed during the cooling process. Furthermore, the OH^– ion content of the crystal increased after annealing experiments. It can be concluded that incorporation of hydroxide ions caused the surface cracking of the as-grown C12A7 crystals.