Structural and electrical characteristic of crystalline barium titanate synthesized by low temperature aqueous method
✍ Scribed by Srimala Sreekantan; Ahmad Fauzi Mohd Noor; Zainal Arifin Ahmad; Radzali Othman; Anthony West
- Publisher
- Elsevier Science
- Year
- 2008
- Tongue
- English
- Weight
- 720 KB
- Volume
- 195
- Category
- Article
- ISSN
- 0924-0136
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✦ Synopsis
Barium titanate powder was processed at temperature 80 • C by reacting TiO 2 sol in aqueous solutions that contained BaCl 2 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 m whereas the large ones approximately 1.5-2.0 m. 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 BaTiO 3 with a secondary phase of BaTi 2 O 5 and Ba 6 Ti 17 O 40 . The ac response of sintered barium titanate indicated that the materials are electrically heterogeneous. Two regions are apparent in this material. The first element (R 1 C 1 ) and the second element (R 2 C 2 ) 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 R 1 and R 2 were 1.60 and 0.90 eV, respectively. C 2 is a ferroelectric material but conclusive behaviour of C 1 could not be determined. Therefore, these components are tentatively assigned to different composition regions: (R 2 C 2 ) is ferroelectric barium titanate whereas (R 1 C 1 ) is Ti-rich secondary phase.