Synthesis and processing of barium titanate ceramics from alkoxide solutions and monolithic gels

Abstract

We report the sol-gel processing of barium titanate (BaTiO{sub 3}) ceramics from methoxyethoxide precursors. The effects of heat treatment on phase and microstructure development for solution- and gel-derived ceramics are reported. Drying of monolithic alcogels yielded the low-temperature (T < 125 {degrees}C) crystallization of BaTiO{sub 3}. Crystallization was associated with gel syneresis. Nanocrystalline BaTiO{sub 3} gels which crystallized before the removal of solvent were used as monolithic precursors for the powderless processing of fine-grain dielectrics. Lower levels of hydrolysis content for solution-derived ceramics led to higher crystallization temperatures for the perovskite phase. In these cases, BaTiO{sub 3} crystallized via an intermediary oxycarbonate phase. The efficiency with which carbonaceous species were eliminated during calcination of powders derived from sols or gels was investigated by thermal analysis, infrared spectroscopy, and helium gas pycnometry. Dielectric properties were determined for dense ceramics derived form monolithic xerogels. Micrographs illustrate the development of structure for ceramics derived form the xerogel precursors. 27 refs., 9 figs.