ZnO varistors with $BaCoO_3_-_x (0.12>x>0)$ as the only formulating phase

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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Abstract

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
Publication:	Materials Research Bulletin
Publisher:	Elsevier Science
Additional Information:	Copyright of this article belongs to Elsevier Science.
Keywords:	zinc;barium;cobaltate;oxides
Department/Centre:	Division of Chemical Sciences > Materials Research Centre
Date Deposited:	23 Jun 2007
Last Modified:	16 Jan 2012 09:52
URI:	http://eprints.iisc.ac.in/id/eprint/11240

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