Synthesis and characterization of Fe3+ doped PbTiO3 nanopowders

A set of Fe3+- modified PbTiO3 nanopowders which is a widely used ferro- and piezo-electric ceramic material has been synthesized according to the combined polymerization and pyrolysis (CPP) route of metallorganic precursors with subsequent calcination at various temperatures. This study aimed to shift the unit cell of PbTiO3 crystals from tetragonal to cubic phase at room temperature by adjusting the optimum reaction time and temperature by doping 0,025 mole % Fe3+and by ball milling the yield. Different reaction temperatures (300-900°C) are tried for the most efficient energy / grain size ratio.In order to obtain PbTiO3 crystals, an organo-metallic sol-gel precursor is used. By applying proper thermal treatment and synthesis route, grain size reduction is succeeded in the order of nanometers (10 ? 400nm range). X-Ray Diffraction and Raman characterization are used to calculate the unit cell parameters, to confirm material identity and purity, as well as to verify the formation of a PbTiO3 perovskitic phase and the existence of ferroelectricity.Furthermore, the prevailing defect structure has been investigated by means of electron paramagnetic resonance (EPR) spectroscopy. The EPR results clearly indicate marked size effects by approaching to the critical grain size (dcrit < 12 nm) at which a size-driven tetragonal-to-cubic phase transition is observed at room temperature. As a function of mean grain size, either ( ) defect dipoles or 'isolated' defects are formed. These results are analyzed in terms of a core-shell model. Accordingly, the obtained Fe3+-modified PbTiO3 nanoparticles consist of a ferroelectric core, a distorted interface region, and a cubic dead layer which is paraelectric.