Raghu, N and Ravi, V and Kutty, TRN (1991) ZnO varistors with $BaCoO_3_-_x (0.12>x>0)$ as the only formulating phase. In: Materials Research Bulletin, 26 (4). pp. 261-268.
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Varistors prepared from $ZnO$ with 1-3 mole% 2H-perovskite, $BaCoO_3_-_x(0.12>x>0)$, have nonlinearity index, $\propto$ , upto 35. Nonlinear resistivity is observed only when the oxygen deficiency of $BaCoO_3_-_x$ is <0.12, together with controlled processing parameters such as the method of mixing, sintering temperature, cooling rate and post-sintering treatment. The nonlinear property originates as a result of higher concentration of $Co(III)$ present at the more insulating grain boundary layers, being charge-compensated by zinc vacancies. Whereas, the grain interiors are conducting because of the donor states arising out of the frozen-in oxygen vacancies,as revealed by the EPR results.
|Item Type:||Journal Article|
|Additional Information:||Copyright of this article belongs to Elsevier Science.|
|Department/Centre:||Division of Chemical Sciences > Materials Research Centre|
|Date Deposited:||23 Jun 2007|
|Last Modified:||16 Jan 2012 09:52|
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