Effects of alumina surrounding in sintering process on ZnO-Bi 2O3varistors doped with CoO
Nonlinear current-voltage properties of zinc oxide-bismuth oxide varistors doped with cobalt oxide were investigated. The composition of ZnO doped with 0.5 mol% Bi2O3 and 0.75 mol%CoO was prepared and sintered in two different surroundings, zinc oxide-bismuth oxide-cobalt oxide powder and alumina po...
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| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
2014
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| Online Access: | http://www.scopus.com/inward/record.url?eid=2-s2.0-9644272421&partnerID=40&md5=b0ae1fec6091c7b9e4e6099c298e91e1 http://cmuir.cmu.ac.th/handle/6653943832/5011 |
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| Institution: | Chiang Mai University |
| Language: | English |
| Summary: | Nonlinear current-voltage properties of zinc oxide-bismuth oxide varistors doped with cobalt oxide were investigated. The composition of ZnO doped with 0.5 mol% Bi2O3 and 0.75 mol%CoO was prepared and sintered in two different surroundings, zinc oxide-bismuth oxide-cobalt oxide powder and alumina powder. Microstructures and element tracing were studied using scanning electron microscopy with X-ray microanalysis, electron probe microanalysis and X-ray diffraction. Results clearly showed that the alumina surrounding led to bismuth loss from the green body and degraded the nonlinear property of varistors. At sintering temperatures higher than 1150°C, the alumina-surrounding sintered specimens became ohmic and the electrical resistivity of 200 Ω cm was found in the specimen sintered at 1200°C. © 2004 Elsevier B.V. All rights reserved. |
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