Raman scattering, microstructural and dielectric studies on Ba1-xCaxBi4Ti4O15 ceramics

Kumar, Sunil and Kundu, Swarup and Ochoa, DA and Garcia, JE and Varma, KBR (2012) Raman scattering, microstructural and dielectric studies on Ba1-xCaxBi4Ti4O15 ceramics. In: MATERIALS CHEMISTRY AND PHYSICS, 136 (2-3). pp. 680-687.

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Abstract

Polycrystalline powders of Ba1-xCaxBi4Ti4O15 (where x = 0, 0.25, 0.50, 0.75 and 1) were prepared via the conventional solid-state reaction route. X-ray diffraction (XRD) and Raman scattering techniques have been employed to probe into the structural changes on changing x. XRD analyses confirmed the formation of monophasic bismuth layered structure of all the above compositions with an increase in orthorhombic distortion with increase in x. Raman spectra revealed a redshift in A(1g) peak and an increase in the B-2g/B-3g splitting with increasing Ca content. The average grain size was found to increase with increasing x. The temperature of the maximum dielectric constant (T-m) increased linearly with increasing Ca-content whereas the diffuseness of the phase transition was found to decrease with the end member CaBi4Ti4O15 showing a frequency independent sharp phase transition around 1048 K. Ca doping resulted in a decrease in the remnant polarization and an increase in the coercive field. Ba0.75Ca0.25Bi4Ti4O15 ceramics showed an enhanced piezoelectric coefficient d(33) of 15 pC N-1 at room temperature. Low values of dielectric losses and tunability of temperature coefficient of dielectric constant (tau(epsilon)) in the present solid-solution suggest that these compounds can be of potential use in microwave dielectrics at high temperatures. (C) 2012 Elsevier B.V. All rights reserved.

Item Type:	Journal Article
Publication:	MATERIALS CHEMISTRY AND PHYSICS
Publisher:	ELSEVIER SCIENCE SA
Additional Information:	Copyright for this article belongs to ELSEVIER SCIENCE SA, SWITZERLAND
Keywords:	Ceramics;Raman spectroscopy and scattering;Electronic characterisation;Ferroelectricity
Department/Centre:	Division of Chemical Sciences > Materials Research Centre
Date Deposited:	04 Jan 2013 06:10
Last Modified:	04 Jan 2013 06:10
URI:	http://eprints.iisc.ac.in/id/eprint/45627

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