Hydrothermal synthesis of lead titanate from complexed precursor solutions

Lead titanate was synthesized at 200 degrees C from chelated titanium and lead in alkaline, aqueous solution. Complexing agents included H2O2 and EDTA, with KOH and KF as mineralizers. After synthesis in hydrothermal autoclaves, the products were examined by field emission scanning electron microscopy (FESEM) and powder X-ray diffraction. Samples prepared with low Ti (< 8 mmolal) and high KOH (>1.2 m) concentrations were found to contain dendritic powder combined with a small fraction of square platelets varying in size from 50-200 mu m. X-ray diffraction confirmed that the yellow powders were single-phase, tetragonal PbTiO3. The conditions under which these platelets were formed (200 degrees C, 200 psi) are mild compared to conventional hydrothermal routes, which require > 500 degrees C and > 10 000 psi to grow crystals of comparable size. (C) 2000 Elsevier Science B.V. All rights reserved.