Polyacrylic acid (PAA) has been chosen to stabilize BaTiO, powder in aqueous solution. Zeta potential studies show that the Ba-rich particle surface is positively charged in the pH range from 2 to 11 without PAA. Adsorption of PAA decreases the zeta potential in acidic solution and changes the surface to a negative charge in basic solution. Adsorption of PAA onto BaTiO, surfaces is found to be related to the pH-dependent PAA conformation in solution. The amount of PAA adsorbed at pH 1.5 is one order of magnitude more than at pH 10.5, due to a more compact polymer conformation. Colloid stability of aqueous BaTiO, suspensions is related to the dissociation of PAA as a function of pH. BaTiO, suspensions can be stabilized at pH values higher than 7, where more than 99% of carboxylic groups are ionized. At pH 10.5, suspension stability is related to the PAA coverage on BaTiO, particle surface. Stabilization can be achieved only when conditions of both PAA ionization and BaTiO, surface coverage are satisfied, suggesting an electrosteric stabilization mechanism. Green density of 62% can be achieved by slip casting at a pH above 10, compared to the best density of 58.6% by isostatic pressing at 242 MPa.

The development of camber during the cofiring of a twolayered structure of Ni-electrode/BaTiO 3 -dielectric as a function of temperature has been investigated. At a given thickness of Ni electrode, less camber and camber rate with increasing thickness of BaTiO 3 dielectric have been observed. This phenomenon is attributed to the densification mismatch between the Ni electrode and the BaTiO 3 dielectric during cofiring. The mathematical analysis of camber development, based on a viscous model, shows significant agreement with experimental observations.

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