Effect of lattice hydroxyl on the phase transition and dielectric properties of barium titanate particles

Abstract

Presence of the hydroxyls in the lattice is believed to be the major cause of the reduced tetragonality in the barium titanate ceramic powder. Commercial barium titanate that is known to be cubic in nature has been used in this study. This sub-micron powder is treated with N-Methyl-2-Pyrrolidinon (NMP) to obtain a tetragonal powder as confirmed by X-ray diffraction analysis, differential scanning calorimetry and the c/a ratio. The dielectric constant of a single particle of this NMP treated cubic powder is reported to be around 64% higher than the as-received cubic powder. To add weight to the hypothesis mentioned hitherto, simulation experiments have been performed by aging in acidic water, with a pH ∼ 3–4 and in basic water, with a pH ∼ 12–13. The as-received cubic barium titanate powder, calcined at different temperatures, has been aged in different pH conditions, acid and basic waters. Then the powder is further used for the characterization of electrical properties. The dielectric properties of the barium titante ceramic powder that is determined does depend inversely on the lattice OH content as confirmed by FT-IR spectroscopic analysis and TGA results.