Process for fabricating ZNO-based varistors
The invention is a process for producing ZnO-based varistors incorporating a metal oxide dopant. In one form, the invention comprises providing a varistor powder mix of colloidal particles of ZnO and metal-oxide dopants including Bi/sub 2/O/sub 3/. The mix is hot-pressed to form a compact at temperatures below 850/sup 0/ C. and under conditions effecting reduction of the ZnO to sub-stoichiometric oxide. This promotes densification while restricting liquid formation and grain growth. The compact then is heated under conditions restoring the zinc oxide to stoichiometric composition, thus improving the varistor properties of the compact. The process produces fine-grain varistors characterized by a high actual breakdown voltage and a high average breakdown voltage per individual grain boundary.
- Assignee:
- The United States of America as represented by the Department of Energy
- Patent Number(s):
- US 4510112
- OSTI ID:
- 5272826
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360101 -- Metals & Alloys-- Preparation & Fabrication
42 ENGINEERING
420800* -- Engineering-- Electronic Circuits & Devices-- (-1989)
BISMUTH COMPOUNDS
BISMUTH OXIDES
CHALCOGENIDES
CRYSTAL DOPING
CRYSTAL STRUCTURE
ELECTRICAL EQUIPMENT
EQUIPMENT
FABRICATION
GRAIN SIZE
HOT PRESSING
MATERIALS WORKING
MICROSTRUCTURE
OXIDES
OXYGEN COMPOUNDS
PRESSING
RESISTORS
SEMICONDUCTOR DEVICES
SEMICONDUCTOR RESISTORS
SIZE
STOICHIOMETRY
ZINC COMPOUNDS
ZINC OXIDES