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Power Preparation Method

IP.com Disclosure Number: IPCOM000062020D
Original Publication Date: 1986-Sep-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

David, LD: AUTHOR [+2]

Abstract

Fine and nearly monosized stress-free single crystals can be prepared by hydrothermal crystal growth under controlled nucleation density. The powder preparation method basically comprises (1) the preparation of an x-ray amorphous mixture of starting materials, (2) heat treatment of the mixture for nucleation and (3) crytal growth in the hydrothermal condition.

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Power Preparation Method

Fine and nearly monosized stress-free single crystals can be prepared by hydrothermal crystal growth under controlled nucleation density. The powder preparation method basically comprises (1) the preparation of an x-ray amorphous mixture of starting materials, (2) heat treatment of the mixture for nucleation and (3) crytal growth in the hydrothermal condition.

The starting powder mixture can be prepared from an aqueous or non- aqueous solution of the appropriate amounts of the chemical constituents. Typically, the mixture can be a mixture of chlorides, sulfates, hydroxides, and/or any other inorganic compounds, or certain organometallic compounds, such as citrates. Optionally, the starting powder mixture can be heat treated in an appropriate atmosphere for preliminary reaction, drying, and/or thermal decomposition, before it is used as the "nutrient" starting material for hydrothermal crystal growth.

Uniform nucleation for crystal growth is accomplished by heat treatment of the nutrient mixture at an appropriate temperature which will vary depending on the materials. The temperature for nucleation is often slightly above the temperatur preliminary reaction, drying, and/or decomposition. Therefore, the heat treatment for nucleation can be combined with other preparatory heat treatments to form a single process prior to the hydrothermal processing.

At a given temperature and pressure, the nutrients in the system dissolve into the fluid, whe...