Preparation of SrBi2Ta2O9 from metal alkoxides

SrBi2Ta2O9 (SBT) has potential application in FERAM. Some problems in the s ol-gel processing of SBT, such as the solubility of metal alkoxides, chemic al modification with a chelating reagent and crystallization behavior of th e gels, are investigated. The starting solutions were prepared with Sr(OC4H9)(2), Bi(OC3H7)(3), and T a(OC2H5)(5). Ethoxyethanol and acetylacetone (ACAC) were used as solvent an d chelating reagent, respectively. Ta- and Bi-alkoxide are chemically modif ied with ACAC, but Sr-alkoxide was not. The SBT solution was stabilized wit h ACAC for ca. 3 months. After hydrolysis of the SBT solution with the addi tion of ACAC, a monolithic and transparent gel was obtained at room tempera ture in 100 days. The X-ray diffraction peaks of SBT and very weak peaks of SrTa2O6 (ST) and SrBi2O4 (SB) were found after calcination at 700 degreesC for both of the gels obtained with and without addition of ACAC. In contra st, the stronger peaks of ST and SB were observed for the powder mixture of SrCO3, Bi2O3, and Ta2O5 after calcination at 800 degreesC. These results s how the better homogeneity of the gels.