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Micrograph 171 and full record

Link to image file for micrograph 171
Micrograph no
171
Brief description
ZnO varistor
Keywords
ceramic Link to MATTER Glossary entry for ceramic, oxygen Link to MATTER Glossary entry for oxygen, varistor, zinc
Categories
Ceramic
System
ZnO
Composition
ZnO containing small amounts of oxides such as Sb2O3 and Bi2O3
Standard codes
Reaction
Processing
Produced using liquid phase sintering: gives rise to a structure consisting of conductive ZnO grains with the additional oxides being preferentially located at grain boundaries.
Applications
Used to short-circuit transient high voltage spikes in electronic devices. Incorporated into circuits, in parallel with the device to be protected. Acts as an insulator below a certain breakdown voltage, but as a conductor at higher voltages, due to highly non-linear I-V relationship.
Sample preparation
Thin section
Technique
Transmitted polarised light microscopy, with sensitive tint plate
Length bar
250 μm
Further information
Contributor
Dr K M Knowles
Organisation
Department of Materials Science and Metallurgy, University of Cambridge
Date
09/08/02
Licence for re-use
Attribution-NonCommercial-ShareAlike 4.0 International
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