Nanometer crystallites in ferroelectric PbTiO3, BaTiO3 ultrafine powders

The PbTiO3, BaTiO3 ultrafine powders with nanometer crystallites are prepared through sol-gel and thermal decemposition of chelate respectively. Particle size is 300 nm in volume. XRD analysis indicates the average crystallite size is 51.2 nm, and c/a ratio is 1.061. TEM observation demonstrates crystalline BaTiO3 particles can be dispersed into crystallites whose sizes are under 100 nm by electronic beam during the observation. DSC and specific analyses indicate that the phase transition of PbTiO3 is of first order, and appears broadened, and the phase transition temperature is lower than that of bulk PbTiO3 material. The mechanism for this phenomenon is discussed.