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Molten Salt Synthesis of Nanocrystalline Phase of High Dielectric Constant Material $CaCu_{3}Ti_{4}O_{12}$

Prakash, B Shri and Varma, KBR (2008) Molten Salt Synthesis of Nanocrystalline Phase of High Dielectric Constant Material $CaCu_{3}Ti_{4}O_{12}$. In: Journal Of Nanoscience And Nanotechnology, 8 (11). pp. 5762-5769.

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Official URL: http://iisc.library.ingentaconnect.com/content/asp...

Abstract

Nanocrystalline powders of giant dielectric constant material, $CaCu_{3}Ti_{4}O_{12}$(CCTO), have been prepared successfully by the molten salt synthesis (MSS) using KCI at 750 degrees C/10 h, which is significantly lower than the calcination temperature (similar to 1000 degrees C) that is employed to obtain phase pure CCTO in the conventional solid-state reaction route. The water washed molten salt synthesized powder, characterized by X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), and Transmission electron microscopy (TEM) confirmed to be a phase pure CCTO associated with similar to 150 nm sized crystallites of nearly spherical shape. The decrease in the formation temperature/duration of CCTO in MSS method was attributed to an increase in the diffusion rate or a decrease in the diffusion length of reacting ions in the molten salt medium. As a consequence of liquid phase sintering, pellets of as-synthesized KCI containing CCTO powder exhibited higher sinterability and grain size than that of KCI free CCTO samples prepared by both MSS method and conventional solid-state reaction route. The grain size and the dielectric constant of KCI containing CCTO ceramics increased with increasing sintering temperature (900 degrees C-1050 degrees C). Indeed the dielectric constants of these ceramics were higher than that of KCI free CCTO samples prepared by both MSS method and those obtained via the solid-state reaction route and sintered at the same temperature. Internal barrier layer capacitance (IBLC) model was invoked to correlate the observed dielectric constant with the grain size in these samples.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to American Scientific Publishers.
Keywords: Ceramic;Molten Salt Synthesis;Dielectric Properties.
Department/Centre: Division of Chemical Sciences > Materials Research Centre
Date Deposited: 04 Nov 2009 07:04
Last Modified: 04 Nov 2009 07:04
URI: http://eprints.iisc.ernet.in/id/eprint/17825

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