Effect of poly(acrylic acid) and poly(vinyl alcohol) on the solubility of colloidal BaTiO3 in an aqueous medium

Abstract

The influence of poly(acrylic acid) (PAA) and poly(vinyl alcohol) (PVA) on Ba dissolution from the BaTiO3-aqueous solution interface was investigated. Incongruent dissolution of Ba impacts the colloidal stability, microstructure, and electrical properties of BaTiO3 and related perovskite dielectric materials used in the manufacture of ceramic capacitors. The solubility characteristics of BaTiO3 were influenced significantly by the presence of PAA and PVA. PAA, which forms weak monodentate complexes with Ba2+, acted as both a passivating and a sequestering agent, depending on pH. Both PAA and PVA provided some degree of passivation in the acidic pH region. Above pH 8, where BaTiO3 solubility decreases sharply, PVA had a moderate passivating effect, whereas solubility was enhanced by PAA with a positive linear dependence on concentration. The adsorptive and electrokinetic behavior of colloidal BaTiO3 with respect to PAA and PVA are correlated with the observed passivating and sequestering properties of these polymers.