Importance

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Abstract

A process and system may be employed to produce large, defect-free oxide crystals with high melting points which may utilize a water-cooled horizontal furnace with a hot zone design comprising multiple independently controllable heaters surrounded by a vapor shield and various layers of thermal insulation of varying thickness and composition. Raw materials such as sapphire crystals or alumina powder may be placed in a crucible or boat that may be positioned to ride on rollers. The crucible may be pulled (or pushed) through a furnace environment surrounded by a vapor shield and insulation at a controlled rate to melt and then crystallize the raw material into a sapphire crystal. The vacuum level may be controlled by a vacuum system attached to the furnace. Process parameters such as power, temperature, pulling speed (i.e., movement speed), heating rates, cooling rates, and chamber pressure may be controlled by a control system which may be configured to take an input from each component of the system and sends the necessary control outputs.

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First Claim