Low temperature hydrothermal synthesis of lead titanate crystallites

A study was conducted to compare the minimum reaction temperatures for the hydrothermal synthesis of pure lead titanate crystallites with precursors I and II. The synthesis conditions (i.e., temperature, pH, and input reagent concentrations) were calculated using a thermodynamic model. A comparison between the theoretically modeled and experimental conditions was made. Although the models predicted reactions as low as 25/spl deg/C, the minimum temperatures for a 72 h reaction time with precursors I and II were 120 and 140/spl deg/C, respectively. Furthermore, by increasing the Pb/Ti molar stoichiometric ratio from 1.0 to 2.0 (with precursor LT) the reaction temperature for phase-pure lead titanate could further be reduced below 90/spl deg/C; while with precursor I phase-pure lead titanate was difficult to obtain and was not obtained below 140/spl deg/C. It can be concluded that precursor composition and stoichiometry influence the reaction temperature.