Current Limiting by n-type Barium Titanate Ceramics having no Positive Temperature Coefficient in Resistance

Kutty, TRN and Ravi, V (1993) Current Limiting by n-type Barium Titanate Ceramics having no Positive Temperature Coefficient in Resistance. In: Materials Research Bulletin, 28 (1). pp. 19-26.

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Abstract

Stable current-limiting characteristics are observed for n-$BaTiO_3$ ceramics which do not exhibit positive temperature coefficient in resistance (PTCR). These ceramics have been prepared by reannealing the sintered polycrystalline n-$BaTiO_3$ after painting on the disks with low melting mixtures of $PbO+Bi_2O_3+B_2O_3$ and thereby modifying the grain boundary layer regions. The power handling capability can be altered by the addition of isovalent lattice substituents as well as the grain boundary layer modifiers such as $Al_2O_3+SiO_2+TiO_2$ and controlling the donor concentrations in the bulk by regulating the oxygen content in the sintering atmosphere. The current-limiting in semiconducting titanates arises out of the combined influence of joule-heating that modifies the diffuse phase transition and the field effect by way of charge carrier tunneling across the asymmetric barriers at the grain boundary regions.

Item Type:	Journal Article
Publication:	Materials Research Bulletin
Publisher:	Elsevier
Additional Information:	Copyright of this article belongs to Elsevier.
Keywords:	Barium;Titanates;Ceramics
Department/Centre:	Division of Chemical Sciences > Materials Research Centre
Date Deposited:	10 Aug 2006
Last Modified:	19 Sep 2010 04:30
URI:	http://eprints.iisc.ac.in/id/eprint/7987

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