The Growth of Large Diameter Single Crystals by Vertical Solidification of the Melt.
ARMY MATERIALS AND MECHANICS RESEARCH CENTER WATERTOWN MA
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Growth of large diameter single crystals, especially of phases which melt at high temperatures and have a high specific gravity, is governed by conditions that quite differ from those which occur during the growth of crystals whose diameter does not exceed 50 mm. This paper defines and analyzes these special conditions and delineates their effect on crystal growth. It is also shown that in spite of the presence of negative factors which are inherent to the growth process of large diameter single crystals, these adverse factors, if recognized properly, can be brought under control to such a degree that the growth of large diameter single crystals can be achieved. The vertical solidification of melt method VSOM is described. This method produces large single crystals, even for binary mixtures with a steep liquidus. Neodymium-doped yttrium aluminum garnet NdYAG crystals have been grown 75 mm in diameter and 100 mm high. These crystals are also water clear. Both size and perfect crystallinity are important for application to lasers. Author