Preparation of LiTaO3 powders at reduced temperatures by a polymerized complex method

A polymerized complex technique was utilized to prepare LiTaO3 at reduced temperatures, viz. 500-600 degrees C. A methanol-citric acid (CA) solution of TaCl5 was found to be highly resistant to ambient moisture in air. Heating of a mixed-solution of methanol, CA, ethylene glycol (EG), Li and Ta ions with a molar ratio of [Methanol]:[CA]:[EG]:[Li]:[Ta] = 1:0.1:0.4:0.01:0.01 at 130 degrees C produced a yellow transparent polymeric gel without any precipitation, which after pyrolysis at 300 degrees C was converted to a powder precursor for LiTaO3. The formation of pure LiTaO3 occurred during the heat treatment of the powder precursor at temperatures higher than 500 degrees C in static air, which was contirmed by a combined analysis using XRD and Raman scattering techniques. No X-ray diffraction and Raman spectroscopic evidence for phase separation of crystalline Li2CO3 and Ta2O5 as distinct intermediates has been obtained during the thermal decomposition of the powder precursor. (C) 1998 Elsevier Science S.A. All rights reserved.