Dissemination of IT for the Promotion of Materials Science (DoITPoMS)

DoITPoMS Micrograph Library Full Record for Micrograph 655

Full Record for Micrograph 655

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Micrograph no
655
Brief description
Small ceramic pot showing centimetre scale crystals within the glaze
Keywords
ceramic Link to MATTER Glossary entry for ceramic, crystalline glaze, devitrification Link to MATTER Glossary entry for devitrification, willemite
Categories
Ceramic
System
Soda-lime-silica glaze
Composition
Soda-lime-silica glaze containing zinc oxide 25, cobalt oxide 0.5 (wt%)
Standard codes
Reaction
Processing
See Further information
Applications
Sample preparation
Technique
Photography (no microscope)
Length bar
5 mm
Further information
Careful heat treatment of the glaze produces a very small number of willemite (zinc orthosilicate, Zn2SiO4) nuclei which can grow to centimetre dimensions over the course of a few hours at a suitably high temperature. Cobalt in the glaze composition segregates preferentially to the willemite crystals, colouring them blue.
Contributor
Dr K M Knowles
Organisation
Department of Materials Science and Metallurgy, University of Cambridge
Date
04/11/02
Licence for re-use
Attribution-NonCommercial-ShareAlike 4.0 International
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