Browse Prior Art Database

Production of High Quality Crystals from High Temperature Solutions

IP.com Disclosure Number: IPCOM000084120D
Original Publication Date: 1975-Sep-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Scheel, HJ: AUTHOR

Abstract

A large seed crystal plate of similar diameter as the desired crystal, e.g., 100 mm diameter, is mounted horizontally on a seed crystal holder which can be rotated at various rates. For growth, the seed is immersed in a high-temperature solution or a melt of the material to be crystallized. Supersaturation and growth is achieved by slow cooling of the saturated solution, by transport of solute from a hot region T2 to the slightly cooler region T1 of the seed crystal, or be transport of one of the crystal constituents, via vapor phase to the growth solution. During growth, the seed is rotated at about 50 to 300 RPM.

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Production of High Quality Crystals from High Temperature Solutions

A large seed crystal plate of similar diameter as the desired crystal, e.g., 100 mm diameter, is mounted horizontally on a seed crystal holder which can be rotated at various rates. For growth, the seed is immersed in a high-temperature solution or a melt of the material to be crystallized. Supersaturation and growth is achieved by slow cooling of the saturated solution, by transport of solute from a hot region T2 to the slightly cooler region T1 of the seed crystal, or be transport of one of the crystal constituents, via vapor phase to the growth solution. During growth, the seed is rotated at about 50 to 300 RPM.

After growth to the desired thickness, the seed is withdrawn from the solution and excess solution spun off by a short increase of the rotation rate to about 1000 RPM. Another way of preventing droplets on the crystal surface consists of tilting the plate from the horizontal plane. The seed holder with the grown crystal plate is slowly brought to room temperature.

The crystallized part is then carefully separated from the seed by cleaving or by careful sawing along plane A-B. The seed crystal is now used for growing a new crystal without being removed from the seed holder. Also, the growth solution can be used again.

If the solution contains volatile solvents, sealed (high-pressure) systems or liquid encapsulants (B(2)O(3)) in combination with a Accelerated Crucible Rotation Technique...