Effects of Molar Ratio of Citric Acid to Cations and of pH Value on the Formation and Thermal-Decomposition Behavior of Barium Titanium Citrate

• Published in: Journal of the American Ceramic Society 1999-06, Vol.82 (6), p.1409-1415
• Main Authors: Tsay, Jenq-dar, Fang, Tsang-tse
• Format: Article
• Language: English
• Subjects: Applied sciences; Building materials. Ceramics. Glasses; Ceramic industries; Chemical industry and chemicals; Electrotechnical and electronic ceramics; Exact sciences and technology; Technical ceramics
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/j.1151-2916.1999.tb01931.x

Several experiments were conducted to examine the effects of the molar ratio of citric acid to cations and of the pH value on the chemistry of a solution prepared by the Pechini method. Two types of precipitates, barium titanium citrate (BTC) and barium citrate, developed, depending on the experimental conditions. Characterization of BTC by FT‐IR spectroscopy and solid‐state 13C‐NMR spectroscopy indicated that barium and titanium ions were chelated simultaneously by the central deprotonated alcoholic ligands and by dissociated carboxylic acid groups with a unidentate type of three citric acid molecules. The possible coordinated structure of BTC was proposed. The thermal decomposition behavior of BTC was investigated by powder X‐ray diffractometry, FT‐IR spectroscopy, and solid‐state 13C‐NMR spectroscopy. During decomposition, the nature of bonding between carboxylate groups and cations changed in the order unidentate → bridging → ionic, and carbonate species were detected at 500°C. A small amount of BaCO3 and the intermediate oxycarbonate coexisted at 550°‐600°C.