Barium titanate powders were produced using either an amorphous hydrous Ti gel or anatase precursor in a barium hydroxide (Ba(OH)2) solution via a hydrothermal technique in order to discern the nucleation and formation mechanisms of BaTiO3 as a function of Ti precursor characteristics. Isothermal reaction of the amorphous Ti hydrous gel and Ba(OH)2 suspension is believed to be limited by a phase boundary chemical interaction. In contrast, the proposed BaTiO3 formation mechanism from the anatase and Ba(OH)2 mixture entails a dissolution and recrystallization process. BaTiO3 crystallite nucleation, studied using high resolution transmission electron microscopy, was observed at relatively low temperatures (38°C) in the amorphous hydrous Ti gel and Ba(OH)2 mixture. Additional solution conditions required to form phase pure crystallites include a CO2-free environment, temperature >70°C and solution pH ≥13.4. Analysis of reaction kinetics at 75°C was performed using Hancock and Sharp's modification of the Johnson-Mehl-Avrami approach to compare observed microstructural evolution by transmission electron microscopy (I).
|Number of pages||14|
|Journal||ACS Symposium Series|
|Publication status||Published - 1998 Dec 1|
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)