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Formation of $BaTiO_3$ from Citrate Precursor

Rajendran, M and Rao, Subba M (1994) Formation of $BaTiO_3$ from Citrate Precursor. In: Journal of Solid State Chemistry, 113 (2). pp. 239-247.

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On thermal decomposition barium bis(citrato)oxotitanate (IV) citrate heptahydrate produces stoichiometric $BaTiO_3$ fine powders at about $650^oC$. Thermal decomposition of the precursor proceeds through three major stages, viz. (i) dehydration, (ii) decomposition of the citrate to form an oxycarbonate intermediate $Ba_2Ti_2O_5CO_3$, and (iii) decomposition of the intermediate carbonate to form $BaTiO_3$. Spectroscopic and thermoanalytical techniques are presently employed to characterize the precursor and the intermediates isolated at various stages. As-prepared $BaTi0_3$ is a mixture of cubic and tetragonal phases. The primary particle size of the powder is on the order of 100 nm, as revealed by the TEM technique. Calcining the powders above 800°C results in the formation of complete tetragonal phase with improved crystallinity. The resultant powders are sinter active to give dense monophasic ceramic compacts having densities in the range 95-99% of the theoretical value. Depending on the processing conditions, the dielectric constant $(\varepsilon_r)$ varies from 1600 to 3000 at 1 kHz, while the dielectric loss, tan 8, ranges from 0.003 to 0.009 at 300 K.

Item Type: Journal Article
Publication: Journal of Solid State Chemistry
Publisher: Elsevier
Additional Information: Copyright of this article belongs to Elsevier.
Department/Centre: Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited: 14 Nov 2006
Last Modified: 19 Sep 2010 04:31
URI: http://eprints.iisc.ac.in/id/eprint/8328

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