Sapphire Growth Method - Heat Exchanger Method (HEM)

Heat Exchanger Method (HEM) is one of sapphire growth method, which is used to grow the sapphire with large size. Since 1970s, Schmid and Viechnicki applied HEM to grow a big sapphire crystal, and the method is used popular and popular. 

Its basic principle is to apply a heat exchanger to dissipate heat, making the crystal growth region forming a longitudinal cold hot temperature gradient. By controlling the volume of gas flow inside heat exchanger and changing the heating powder, the gradient can be kept. Then the crystal can grow slowly from the bottom to the upper part. Following is a pic to show the structure and principle of the growing method.  

Tungsten crucible is used in the middle of furnace, and sapphire is growing in the crucible.      

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