A surface coating method was used t

A surface coating method was used to modify the CSP for BaTiO3 ceramics. Bulk densities up to ∼96% theoretical were obtained by cold sintering at 220 °C and 500 MPa. No Ti-rich amorphous layer forms on the surface of the coated powder, which had high activity. This facilitates the dissolution-precipitation process during the CSP and greatly enhances the ceramic density. Ba vacancies exist at the surface of the coated powders, so Ba(OH)2 solution was used to compensate Ba ions in the as-cold-sintered ceramics. The dielectric permittivity increased after compensation of the Ba ions. Post-annealing at 700 and 900 °C increases the relative density to 97%, and the resulting relative dielectric permittivities are 810 and 1550, respectively, at room temperature and 1 kHz.