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

Abstract

Monophasic oxides of the formula, Ba_1−xPb_xTiO₃ (0≤ x≤1.0) were obtained at temperatures close to 500 °C 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 °C) for the x=0.5 composition. X-ray line broadening studies of 900 °C 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 (var epsilon) decreases with lead-doping having a value 70 for PbTiO₃. The dielectric loss (ε) for different compositions varied between 0.005 and 0.01 at 100 kHz. The dielectric constant and loss show excellent frequency stability.