Electrical characteristics of BaTiO3 ceramics from hydrothermal prepared powders

BaTiO3 nanopowders were synthesized by hydrothermal method: treatment at 150 °C or 250 °C for 7 h of a mixture of TiCl3 and BaCl2 or TiO2 and BaCl2. After sintering treatment at 1250 °C in air for 10 h or 20 h, the corresponding ceramics were obtained and characterized. The ceramics present a heterogeneous microstructure, depending of the nature of the precursor. The grain size and the grain size distribution in the ceramic bulk are directly related to the powder characteristics, and they govern the electrical properties. For small grain size with low grain size distribution, the permittivity at room temperature is large and the Curie temperature is 100 °C. For large grain sizes in very small grains matrix, the permittivity at room temperature is slightly lower and the phase transition occurs at higher temperature (120 °C).