Microstructure and Permittivity of Sintered BaTiO3: Influence of Particle Surface Chemistry in an Aqueous Medium

Published

January 1, 2004

Author(s)

S K. Lee, U Paik, Vincent A. Hackley, Y S. Jung, K J. Yoon

Abstract

The influence of changes in the surface chemistry of colloidal BaTiO₃, due to the dissolution and adsorption/precipitation of Ba in an aqueous medium, on the microstructural development and permittivity of sintered BaTiO₃ powder compacts was investigated. For stoichiometric BaTiO₃conditioned at pH 3 (resulting in a Ti-excess surface layer), grain growth is enhanced at 1350 C and permittivity is reduced with increasing sintering temperature due to the liquid phase formed at grain boundaries. This sample shows minimal grain growth and some moderate enhancement of sinterability at 1300 C compared to the stoichiometric sample (prepared at pH 9). The eutectic liquid phase formed at grain boundaries above 1332 C results in enhanced grain growth. For sintering below the eutectic temperature, grain growth in the pH 3 conditioned sample is minimal and very similar to the stoichiometric sample (processed at pH 9), with some moderate enhancement of sintering due to sliding of the Ti-excess surface phase. Stoichiometric BaTiO₃ treated at pH 3 and subsequently adjusted to pH 10 produces a varying stoichiometry near the grain interface and results in a core-shell structure. This material shows abnormal grain growth at 1350 C due to the heterogeneous adsorption/precipitation of Ba²⁺ ions onto the Ti-excess particle surface, with a contemporaneous and relatively large decrease in permittivity. Sintering of the pH 3/pH 10 conditioned powder at 1300 C results in a permittivity similar to the stoichiometric powder conditioned at pH 9, in spite of significant microstructural coarsening.

Citation

Materials Research Bulletin

Volume

39

Issue

No. 1

Pub Type

Journals

Keywords

aqueous process, barium titanate, ceramics, dissolution, electrokinetics, microstructure, permittivity, precipitation, surface chemistry

Citation

Lee, S. , Paik, U. , Hackley, V. , Jung, Y. and Yoon, K. (2004), Microstructure and Permittivity of Sintered BaTiO₃: Influence of Particle Surface Chemistry in an Aqueous Medium, Materials Research Bulletin (Accessed April 23, 2024)