Structural and electrical characteristic of crystalline barium titanate synthesized by low temperature aqueous method

Barium titanate powder was processed at temperature 80 °C by reacting TiO2 sol in aqueous solutions that contained BaCl2 and NaOH at atmospheric pressure. Well-crystallized (cubic phase), spherical barium titanate powder with average size of 35 nm was formed by this method at 80 °C. As for sintered barium titanate, observation via SEM showed bimodal distribution of grain size. The fine grains was in the range of 0.3–0.5 μm whereas the large ones approximately 1.5–2.0 μm. Furthermore, interesting features such as wedge shape lamellar domains, and {1 1 1} twins formation were observed in the sintered sample. Sintering at 1300 °C, led to the formation of a tetragonal structure BaTiO3 with a secondary phase of BaTi2O5 and Ba6Ti17O40. The ac response of sintered barium titanate indicated that the materials are electrically heterogeneous. Two regions are apparent in this material. The first element (R1C1) and the second element (R2C2) are roughly comparable volume fraction because magnitudes of the capacitance value are similar but they differ in their resistances by 1–2 orders of magnitude, depending on temperature. Activation energy for conductivity for R1 and R2 were 1.60 and 0.90 eV, respectively. C2 is a ferroelectric material but conclusive behaviour of C1 could not be determined. Therefore, these components are tentatively assigned to different composition regions: (R2C2) is ferroelectric barium titanate whereas (R1C1) is Ti-rich secondary phase.