To exclude the effect of calcinatio

To exclude the effect of calcination, the hydrothermal synthesized powders without coating were calcined at 600 °C for 2 h, and the ceramics were prepared by using the CSP. By applying water solution, relative densities of 70% and 65% were obtained for the ceramic made from the hydrothermal synthesized powders and the hydrothermal synthesized powders calcined at 600℃, respectively. We adopted a theoretical density of 6.02 g/cm3 for the BaTiO3 ceramics. Adding a few drops of water during the CSP did not help densify the uncoated BaTiO3 powder into a dense ceramic. The BaTiO3 ceramics were then made from the coated powders. Table 1 shows the densities of the cold-sintered BaTiO3 ceramics made by using the various coated powders, the coating conditions, and the corresponding abbreviations of the coated powders and ceramics. Upon applying just a few drops of water, the relative densities of the BaTiO3 ceramics prepared from coated powders increases to 90% and upwards. The maximum relative density of the BaTiO3 ceramics prepared by the CSP is 96%.