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Vertical Gradient Freeze Growth of Garnet Crystals

IP.com Disclosure Number: IPCOM000086988D
Original Publication Date: 1976-Nov-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Blum, SE: AUTHOR

Abstract

In the magnetic bubble domain technology it is often desirable to have good garnet crystals as substrates for magnetic bubble domain materials. Generally, these substrates are obtained by Czochralski crystal-pulling techniques. The present invention uses a vertical-gradient freeze technique for growing these crystals.

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Vertical Gradient Freeze Growth of Garnet Crystals

In the magnetic bubble domain technology it is often desirable to have good garnet crystals as substrates for magnetic bubble domain materials. Generally, these substrates are obtained by Czochralski crystal-pulling techniques. The present invention uses a vertical-gradient freeze technique for growing these crystals.

In the present technique, a garnet charge is melted in a containing crucible in a high temperature furnace. A positive vertical temperature gradient is established with the melt-seed crystal interface at the melting point. The furnace is then slowly cooled and the crystal grows upward from the seed crystal to the top of the melt.

This vertical-gradient freeze technique requires less complicated and costly equipment than the Czochralski crystal-pulling technique. Further, it has the potential of using much cheaper Pt-Rh alloys rather than iridium for the seed-containing crucible. The technique is readily adaptable to process control and automation. Additionally, the following advantages are obtained: (1) A planar growing interface is obtained, and, hence, minimum coring and attendant defects occur. (2) Excellent crystal diameter control. (3) Large diameter crystals can be grown. (4) The crystal is less strained because the process of crystallization and cool-down to room temperature can

be achieved with very small temperature gradients. (5) Growth striae are eliminated. (6) Crystals having low disloc...