Synthesis of fine Ca-doped BaTiO{sub}3 powders by solid-state reaction method - Part II: Rheological study on milling

摘要

The observations and explanations for the rheological behavior associated with the slurry processing for Ca-doped BaTiO{sub}3 synthesis are included in this second part of our report. The optimum slurry conditions containing three ceramic constituents were decided by using a mixture rule after the determination of each constituent's optimum condition. This approach was quite applicable based on the reproducibility test in determining the parameters such as water to ceramic ratio and dispersant content. In addition, a small amount of NH{sub}4OH addition without any further addition of liquid medium or dispersant was very effective in lowering the slurry viscosity when it was too high to operate the mill in our system. The optimum slurry pH range of 8.5-10.0 was suggested for high energy milling based on the experimental results. Possible models to explain this rheological behavior are also presented in terms of electrosteric mechanism and ionic exchange of dispersant molecule.