# Grain size effects on the dielectric properties of ferroelectric $Bi_2VO_{5.5}$ ceramics

Prasad, KVR and Raju, AR and Varma, KBR (1994) Grain size effects on the dielectric properties of ferroelectric $Bi_2VO_{5.5}$ ceramics. In: Journal of Materials Science, 29 (10). pp. 2691-2696.

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## Abstract

Dielectric properties and microstructural characteristics of ferroelectric bismuth vanadate $(Bi_2VO_{(5.5)})$ ceramics exhibiting grain sizes of 7, 10, 20 and 25 gm have been studied.Microstructural studies indicate the presence of ferroelectric $90^o$ domain patterns on the surface as well as in the bulk of the coarse-grained ceramics. The dielectric constant and the loss tangent both at room temperature and in the vicinity of the Curie temperature have been found to increase with increasing grain size. The Curie temperature (725 K) is found to shift slightly (by about 7 K) towards higher temperatures as the grain size increases (7-25 {\mu}m). The magnitude of the dielectric anomaly around 725 K is found to be higher for coarse-grained ceramics. The dielectric constant and the loss have been found to decrease with increase in frequency (1-1 O0 kHz) for all the ceramics studied. The increase in dielectric constant with increasing grain size is attributed to a decrease in thickness of the relatively more insulating grain boundary layer.

Item Type: Journal Article http://dx.doi.org/10.1007/BF00356819 The copyright belongs to Springer Netherlands. Division of Chemical Sciences > Materials Research Centre 23 Jun 2006 19 Sep 2010 04:29 http://eprints.iisc.ernet.in/id/eprint/7695