Nanometer crystallites in ferroelectric PbTiO₃, BaTiO₃ ultrafine powders

Abstract

The PbTiO₃, BaTiO₃ ultrafine powders with nanometer crystallites are prepared through sol-gel and thermal decomposition of chelate respectively. Particle size is 300 run 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.