Importance

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Abstract

The invention is directed to an apparatus, system and methods for growing high-purity crystals of substances that are peritectic at atmospheric pressure using the Czochralski technique. The apparatus includes a pressure vessel that contains a pressurized gas. The apparatus also includes a cooling unit that is situated in the pressure vessel. The cooling unit receives a coolant flow from outside of the vessel, and has cooled surfaces that define an enclosure that receives the charge material. The apparatus further includes an inductive heating element situated in the vessel, that is coupled to receive electric power externally to the vessel. The element heats the interior portion of the charge material to form a molten interior portion contained by a relatively cool, exterior solid-phase portion of the charge material that is closer relative to the molten interior, to the cooled surfaces of the cooling unit. Because the exterior portion is the same material as the contained molten interior portion, few impurities are introduced to the molten interior portion of the charge material. Due to the pressure exerted by the gas contained in the vessel, the liquid interior of the charge material becomes congruently melting to prevent its peritectic decomposition. Therefore, crystals of substances that are peritectic at atmospheric pressure, can be produced from the liquid phase with the apparatus of this invention using the Czochralski technique. In addition to electric power, the heating element receives a coolant flow from a feedthrough that extends through a wall of the pressure vessel. In proximity to the vessel wall, the feedthrough has two coaxial conductors to improve the electric power transfer to the heating element and to reduce heating of the external surfaces of the vessel. The two conductors of the feedthrough are cylindrical in shape, and define two channels for channeling a coolant flow to and from, respectively, the heating element. A shield formed of a cylindrical sheet of metal, for example, is positioned in the vessel to surround the heating element to focus energy emitted by the element to the charge material.

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First Claim