부산대학교 도서관

We studied the application of the sol-gel method for synthesis of powders from the titanate phases Bi4Ti3O12 and Bi12TiO20 on the basis of hydrolysis-condensation reactions in acetic and nitric acid medium. The phase formation was traced during the heat treatment in temperature range from 25 to 600°C. The used precursors for the synthesis were bismuth nitrate Bi(NO33)3.5H2O and titanium butoxide Ti(OBu)4. Two different routes of sol-gel synthesis were realized according to the used solvents for Bi(NO3)2.5H2O - acetic or nitric acid. The results of X-ray diffraction analysis show that the phase formation mechanism is similar for both routes of synthesis. Complete crystallization takes place at 600°C with main crystalline phases corresponding to the stoichiometrical compounds Bi4Ti3O12 or Bi12TiO20. These data are confirmed by IR spectroscopy and scanning electron microscopy. Conclusions are drawn that the proposed options for sol-gel synthesis are appropriate routes for obtaining the phases Bi4Ti3O12 and Bi4Ti3O12 at lower temperature (600°C) as compared to other methods. [ABSTRACT FROM AUTHOR]