Process for fabricating ZnO-based varistors

Patent · Mon Dec 31 23:00:00 EST 1984

OSTI ID:865403

Lauf, Robert J ^[1]

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1. Oak Ridge, TN

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.degree. 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.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN
• DOE Contract Number: W-7405-ENG-26
• Assignee: United States of America as represented by United States (Washington, DC)
• Patent Number(s): US 4510112
• OSTI ID: 865403
• Country of Publication: United States
• Language: English

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850
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colloidal
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dopants
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heated
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liquid form
metal
metal oxide
metal-oxide
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oxide
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process produces
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reduction
restoring
restricting
stoichiometric
stoichiometric composition
sub-stoichiometric
temperatures
temperatures below
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zinc
zinc oxide
zno
zno-based
zno-based varistors