Preparation and phase transition of nanophase ferroelectric PbTiO 3 fine powders

Nanophase ferroelectric PbTiO₃ (PT) fine powders are prepared through sol-gel and hydrolysis-aging processes. The lattice constants and grain size are determined by XRD, (X-ray diffraction) analysis. The phase transition is examined by DSC (differential scanning calorimetry) analysis with different heating rates. The relation of onset temperature to grain size is obtained. Results indicate that the grain size is in the range of 10-100 nm, that the phase transition temperature is lower than that of bulk material, and that the transition region is broadened. The distribution of particle size may be responsible for the broadening of the phase transition. The phase transition of PT fine powders is compared with the diffused phase transition in relaxor ferroelectrics. The nm structure, nm transition, and critical size of fine powders are discussed