Growing Single Crystal Corundum Tubes by Verneuil Technique in Stable Conditions

The authors analyze the process of corundum tube growth by modified Verneuil's method from the viewpoint of its stability. The article shows that the process is stable in the case of thin‐walled tubes and becomes unstable when the tube wall thickness exceeds a certain critical value which is known to be below the capillary constant. The critical thickness of the tube wall grows with a decrease of the heat flux density differential from the burner along the furnace muffle and with an increase of the tube's outer radius. As a result of a process of crystal growth under preset conditions constant cross‐section single crystaal corundum tubes have been obtained. [Russian text ignored]