Microstructural and dielectric properties of donor doped $(La^{3+})CaCu_3Ti_4O_{12}$ ceramics

Shri Prakash, B and Varma, KBR (2006) Microstructural and dielectric properties of donor doped $(La^{3+})CaCu_3Ti_4O_{12}$ ceramics. In: Journal of Materials Science: Materials in Electronics, 17 (11). pp. 899-907.

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Abstract

Abstract The effect of $La^{3+}$ doping on $Ca^{2+}$ sites in $CaCu_3Ti_4O_{12}$ (CCTO) was examined. Polycrystalline samples in the chemical formula $Ca_{(1-x)}La_{(2/3)x} Cu_3Ti_4O_{12}$ with x = 0, 0.5, 1 were synthesized via the conventional solid state reaction route. X-ray powder diffraction analysis confirmed the formation of the monophasic compounds and indicated the structure to be remaining cubic with a small increase in lattice parameter with increase in $La^{3+}$ doping. The dielectric and impedance characteristics of $Ca_{(1-x)}La_{(2/3)x}Cu_3-Ti_4O_{12}$ were studied in the 100 Hz–10 MHz frequency range at various temperatures (100–475 K). A remarkable decrease in grain size from 50 lm to 3–5 lm was observed on $La^{3+}$ substitution. The dielectric constant of $CaCu_3Ti_4O_{12}$ decreased drastically on $La^{3+}$ doping. The frequency and temperature responses of dielectric constant of $La^{3+}$ doped samples were found to be similar to that of $CaCu_3Ti_4O_{12}$. The effects of $La^{3+}$ doping on the electrical properties of $CaCu_3Ti_4O_{12}$ were probed using impedance spectroscopy. The conducting properties of grain decreased while that of the grain boundary increased on $La^{3+}$ doping, resulting in a decrease of the internal barrier layer effect. A decrease in grain boundary capacitance and stable grain response in $La^{3+}$ doped CCTO ceramics were unambiguously established by modulus spectra studies.

Item Type:	Journal Article
Publication:	Journal of Materials Science: Materials in Electronics
Publisher:	Springer Netherlands
Additional Information:	Copyright of this article belongs to Springer Netherlands.
Department/Centre:	Division of Chemical Sciences > Materials Research Centre
Date Deposited:	08 Nov 2006
Last Modified:	19 Sep 2010 04:32
URI:	http://eprints.iisc.ac.in/id/eprint/8893

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