The Role of Material Chemistry in Processing BaTiO₃ in Aqueous Suspensions

Abstract

The application of material chemistry concepts to processing powder suspensions including solution thermodynamics will be demonstrated on several material systems, notably the complex metal oxide, barium titanate, in aqueous environments. After a discussion of the relevant thermodynamic and kinetic issues for fine particles in liquids, various characterization approaches to understand and control the behavior of powders in liquids will be discussed. Various colloidal characterization techniques, high‐resolution TEM, and chemical analyses of both the solution and solid exposed to solution have been used to study the nature of the chemical reactions and subsequent altered surface layers in the barium titanate–water system. The key factor in developing an effective aqueous processing scheme for any water sensitive material (and all metal oxides are water sensitive) in aqueous suspension, is recognition that deleterious surface hydrolysis reactions must be prevented. It is shown that local chemical inhomogeneities play a role in abnormal grain growth in the barium titanate system exposed to aqueous environments, but can be controlled with appropriate chemical passivation approaches. The success of a passivation–dispersion approach in the aqueous processing of these materials will be discussed as well as the implementation of the general concept of material chemistry approaches to the aqueous processing of other water sensitive materials.

Solubility and aging of lead magnesium niobate in water

“…Because broad distribution of the grain sizes may affect the desirable electric properties [11]. In our study it was shown that there is considerable amount of Pb 2+ and Mg 2+ ion dissolution from the PMN surface.…”

“…However, in Pb-Mg-Nb-H 2 O system A-site cations, Pb 2+ and Mg 2+ , are soluble that makes the surface chemistry more complex compared to other perovskites such as BaTiO 3 and PZT. Adair et al [11] reported the dissolution types dictated by the ceramic materials and solution pH. According to their work, the most multi-component metal oxides such as barium titanate generally follow incongruent type dissolution and the dissolution mechanism strongly depends on the pH value.…”

“…In perovkites the cation at the A site is generally soluble in water whereas the B site cation that is only slightly soluble overall the practical pH range. Therefore, A site cation undergoes incongruent dissolution leaving an interface which is relatively rich in the B site cation [11].…”

Adsorption of anionic polyelectrolyte and comb polymers onto lead magnesium niobate

“…On the other hand perovskite materials having the general chemical formula, ABO 3 such as PMN are composed of a cation or more than one cation at the A site that is generally soluble in water and a cation at the B site that is only slightly soluble over the most of the pH ranges [10]. Therefore, the leaching of lead magnesium niobate in water is a major issue in colloidal processing.…”

Dielectric Studies of Nano Structured BaTi_1-XSn_xO₃ Solid Solutions

“…BaTiO 3 has been extensively investigated and several methods of preparation of high purity, homogeneous, reactive fine BaTiO 3 powders at low temperatures have been reported [3][4][5]. These methods include solid state sintering route, co-precipitation, sol-gel, hydrothermal and co-precipitation plus inverse micro-emulsion method.…”