Microstructure and Permittivity of Sintered BaTiO3: Influence of Particle Surface Chemistry in an Aqueous Medium
S K. Lee, U Paik, Vincent A. Hackley, Y S. Jung, K J. Yoon
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.
, Paik, U.
, Hackley, V.
, Jung, Y.
and Yoon, K.
Microstructure and Permittivity of Sintered BaTiO<sub>3</sub>: Influence of Particle Surface Chemistry in an Aqueous Medium, Materials Research Bulletin
(Accessed June 3, 2023)