Equipment for growing sapphire crystals, etc.
Equipment for growing sapphire crystals is an automated electric furnace for growing single crystal of modified sapphire using the kyropoulos method.
Sapphire crystals grown from the melt. Substances most suitable for growing from the melt, are those that melt without decomposition, have no polymorphic transitions and are characterized by low chemical activity.
In kyropoulos method monocrystalline seed embodied in a water-cooled crystal holder, is brought into contact with the melt in the crucible. In this seed there is a gradual buildup of crystal in the shape of a hemisphere. While the crystal grows as if in the melt. When a growing crystal approaching the wall of the crucible, the crystal holder with the crystal rises a few mm and then continues further growth until the next expansion to the walls of the crucible, the subsequent lift, etc. After each lift on the side of the crystal surface remains circular labels — traces of the transition from one level to another. Thus, when grown using the kyropoulos method , the diameter of the grown crystal is limited only by the size of the crucible and almost can reach 300 cm or more.
In a modified kyropoulos method is the periodic lifting of the chip carrier with a growing crystal is carried out continuously rise with constant speed. The growth is performed from a tungsten crucible in a high vacuum, for which purpose resistive tungsten heater. Growing single crystals is carried out directly in the melt by a gradual decrease in temperature. The speed of the growing crystal, the pulling speed of the growing crystal is set deliberately low (around 0.2 mm/h) to avoid possible formation in single crystals of different kinds of inclusions, blocks and small angle boundaries. Linear decrease of temperature and the constancy of the speed of extrusion leads to the formation of crystals pear shaped with increased density of pores in the nose and tail zones of the crystal.
– high quality products
– automation of growing single crystals.