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.