Synthesis and Ferroelectrical Properties of Lead Titanate Particles by Hydrolysis and Condensation of Complex Alkoxide in Octanol/Acetonitrile Solutions

An attempt was made to produce lead titanate particles with a sol-gel process which adopted the hydrolysis and condensation reactions of complex alkoxide prepared from Pb (O-i-C3H7)2 and Ti(OC2H5)4. The synthetic reactions of the complex alkoxide were carried out in octanol for 2-72h at 70°C, and the successive hydrolysis and condensation reactions were performed at water concentrations of 0.1-2.3mol/dm3 at an ambient temperature in octanol-butanol solvents containing acetonitrile as a cosolvent. Size distributions of the lead titanate particles formed were measured with dynamic light-scattering. Selection of reaction conditions enabled the synthesis of spherical particles with average diameters less than 100nm in ranges of water concentrations of 0.5-2.0mol/dm3 and acetonitrile concentrations of 15-20 vol% at a total monomer concentration of 0.05mol/dm3. The particles were subjected to heat treatment at various temperatures. The particles started to crystallize into a tetragonally perovskite structure at 200°C, and transformed into a single phase at 750°C. Dielectric constants of the particles heat-treated at 500-750°C were close to that of bulk, whereas the crystallite sizes in the particles were similar to the sizes of the particles produced in the reactions.