Advances in the synthesis of ZnO materials for varistor devices

Ramesh Raghavendra, Suresh Pillai, John Kelly, Declan McCormack

    Research output: Contribution to journalArticlepeer-review

    136 Citations (Scopus)


    ZnO based varistors are widely used for overvoltage protection in many electrical and electronic circuits, at voltages ranging from a few to over a million volts. By careful control of the microstructure, through nanostructuring by chemical routes, it should be possible to produce varistors with high breakdown voltage (Vc), as this is proportional to the number of active grain boundaries in the sintered body. This property is particularly important for the production of the small-sized varistors needed for modern electronic instruments such as tablet computers and mobile phones. The current review will outline the recent advances in the chemical processing (e.g. sol–gel, combustion synthesis plasma pyrolysis, micro-emulsion synthesis and precipitation routes) of varistors from ZnO nanomaterials and the properties of these materials. Uncontrolled grain growth at higher temperature is highlighted as a major challenge for obtaining desirable electrical properties for nano-varistors. Various novel sintering techniques such as step-sintering, spark plasma and microwave sintering methods are expected to deliver a varistor with controlled grain growth and optimum electrical characteristics.
    Original languageEnglish
    Pages (from-to)3268-3281
    JournalJournal of Materials Chemistry
    Issue number1
    Publication statusPublished - 2013


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