Industrial furnace. Fig. 3 Schematic representation of the Kyropoulos method. Pull. Seed. Crucible. Crystal. Melt. Bottom heater. Thermal insulation. Side heater . The Czochralski (CZ) method of crystal growth was discovered in by Jan In the Kyropoulos method, pure alumina powder is placed in a crucible and. Kyropoulos method. The method was developed in and consists from smooth crystal growth at low temperature gradient. And lowered melt level.

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Kyropoulos process

The Kyropoulos method for quickly growing the large-size sapphire single crystal is greatly improved on the basis of the conventional Kyropoulos method, and has the advantages of shorter growth period, larger size and higher quality of the grown crystal, higher yield of the crystal, lower unit production cost and the like. Continuously changing conditions of heat exchange and difficulties of mehhod the course of crystal growth necessitate automation of the process.

The size methid aspect ratio of the crucible is close to that of the final crystal, and the crystal grows downward into the crucible, rather than being pulled up and out of the crucible as in the Czochralski method.

A linear temperature decrease and a constant pulling rate lead to the formation of pear-shaped crystals with somewhat elevated pore density in the nose and tail parts of the crystal. A Reprint Collection”, Ed. Processes of charging, vacuumizing, heating for melting, auxiliary temperature field adjustment, crystal leading, shoulder extending, shoulder contracting, equal-diameter growth, pull-off, cooling annealing and discharging are finished in a growth furnace of the large-size sapphire single crystal.

In the modern implementation of HEM, a sapphire seed crystal is placed at the bottom of a crucible which is then loaded with pure alumina crackle, a byproduct of the Verneuil process. So inSpyro Kyropulos developed a process for direct crystallization of the melt by decreasing the boule’s temperature while still in the crucible.


The first of these is observed at the initial growth stage and corresponds to the increase in radiant heat removal from the growing seed. Kyropoulous Method The Czochralski method poduced material in thin crystal filaments, and Verneuil boules had basic dimensional limitations. The EFG method provides the ability to produce various shapes that are not possible with other technologies, and therefore saves costs associated with machining and other finishing processes.

Crystal growth equipments for sapphire crystals using the Kyropoulos method

Kytopoulos CNB en. Intechnician Harold Labelle was enlisted by Tyco Industries in Waltham, MA to develop a process for growing sapphire fibers as reinforcement for metal-matrix compounds. Verneuil developed a flame fusion process to produce ruby and sapphire.

After the cooling step after annealing iyropoulos hours, open the intake valve, pressure in the furnace and the single crystal outside the same, closed cooling water system, crystal lid open, remove the sapphire single crystal, complete the process.

Method for preparing synthetic sapphire by micro-pulling and shoulder-expanding at cooled center. In contrast with the Czochralski kyripoulosthe Kyropoulos process crystallizes the entire feedstock volume into the boule.

After 5 hours, open the intake valve, pressure in the furnace and the single crystal outside the same, closed cooling water system, crystal lid open, remove the sapphire single crystal, to complete the process. Attempts to produce extra large boules using this method have proven largely unsuccessful due to kyropouloe during the cooling process.

One evening, Czochralski left a crucible with molten tin on his desk and began writing notes. The resulting crystals typically have curved growth striations, which limits their use in optical applications.

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The process also allows for tight control over crystal orientation. The resulting sapphire has good optical qualities, and is used widely in lasers, infrared and ultraviolet windows, transparent electronic substrates, high-temperature process windows, and other optical applications.


The Czochralski CZ method of crystal growth was discovered in by Jan Czochralski — and was the fortunate result of an accident and insightful observation.

After 15 hours after the step of closing the shoulder, when the crystalline mass reaches 5 kg, at a speed O. A precisely oriented seed crystal is dipped into the molten alumina. Method for preparing 6-inch P-type solar silicon single crystals through Czochralski method and zone melting method.

Kyropolous grown sapphire is ideal for many optical applications including electronics substrates, IR detectors, fiber-optic lensesoptics windows, missile domes, lenses, probes, lasersand manufacturing. The primary use kyrooulos Verneuil-grown sapphire and ruby today is still for synthetic sapphire and ruby gemstones, watch jewels and watch windows.

Kyropoulos process – Wikipedia

After being modified by the State Optical Institute in Russia, this method became applicable to the growth of sapphire. From Wikipedia, the free encyclopedia. Result of this is crystallization of the end of a refrigerator with the subsequent formation of hemisphere. Heat and vacuum help purify the alumina by vaporizing impurities. EFG-produced crystal material is typically of low to medium optical quality, and can be precisely produced in different crystallographic orientations A, C, random.

The process is named for Kyopoulos Kyropoulos, who proposed the technique in as a method to grow brittle alkali halide and alkali earth metal crystals for precision optics. The furnace is evacuated and heated to melt the crackle while keeping the seed just below its melting point by passing helium gas through the heat exchanger beneath the center of the crucible.