Polymeric citrate precursor route to the synthesis of nano-sized barium lead titanates

Monophasic oxides of the formula, Ba1-xPbxTiO3 (0 less than or equal to X less than or equal to 1.0) were obtained at temperatures close to 500 degreesC from polymeric precursors formed using citric acid and ethylene glycol. These oxides were found to be tetragonal for all values of x, the distortion increasing with Pb content. Differential scanning calorimetry (DSC) shows that the decomposition of the precursor to the oxides varies with composition and the decomposition temperature is highest (530 degreesC) for the x = 0.5 composition. X-ray line broadening studies of 900 degreesC sintered samples show grain size of 50-54 nm in all compositions. TEM studies show agglomerated grains of the size, 40-60 nm. The dielectric constant (e) decreases with lead-doping having a value 70 for PbTiO3. The dielectric loss (D) for different compositions varied between 0.005 and 0.01 at 100 kHz. The dielectric constant and loss show excellent frequency stability.