ScAlMgO_4晶体的生长缺陷

采用提拉法生长出φ30 mm×55 mm的ScAlMgO4晶体。在晶体生长过程中有轻微的挥发,粉末X射线衍射分析表明:挥发物质为MgO单相。运用扫描电镜、光学显微镜以及高分辨X射线衍射仪对晶体中的包裹物、开裂、生长条纹和小角晶界缺陷进行了研究。结果表明:温度梯度和热应力是形成晶体中缺陷的主要原因。通过合理设计温场,控制固-液界面的形状及冷却过程的降温速率,可以提高晶体的完整性。

ScAlMgO<inf>4</inf> crystal with a diameter of 30 mm and a length of 55 mm was grown by the Czochralski method. There was slight volatilization during the growth process. The powder X-ray diffraction (XRD) pattern reveals that the volatile substance is single-phase MgO. The defects in the as-grown crystal, including inclusions, cracks, growth striation and small-angle grain boundary were studied by scanning electron microscopy, Leitz optical microscopy and high resolution XRD. The results show that the main origins of the production of defects are axial temperature gradient and thermal stress in crystal. Crystal perfection can be improved by strategically designing the temperature field, controlling the solid-liquid interface shape and reducing the cooling speeds during the crystal growth.