We use the coated powders of 3-5 wi

We use the coated powders of 3-5 with a relatively high ratio Ba/Ti to discuss the dielectric properties of the as-cold-sintered ceramics. Fig. 9 compares the permittivity loss as a function of temperature for ceramics processed under different conditions. Fig. 9(a) and 9(b) show the dielectric properties of the ceramics with added water or Ba(OH)2 solution, respectively. The results show that, at room temperature, the ceramic with added Ba(OH)2 solution has higher relative dielectric permittivity than the ceramic with added water (~185 vs ∼127 at 1 kHz). The enhanced dielectric permittivity is caused by the compensation of Ba upon adding Ba(OH)2 solution, which reduces the Ba vacancies. In addition, a wide-ranging diffuse dielectric anomaly appears in both ceramics because the coated powders remain a part of the tetragonal phase. The as-cold-sintered ceramics were post-annealed at 700 and 900 °C, and the relative dielectric permittivity increases. As shown in Fig. 9(c) and 9(d), the dielectric constant increases from ∼185 to ∼810 at room temperature (1 kHz) after annealing at 700 °C, and then rises to ∼1550 if further annealed at 900 °C. This indicates that the post-annealing process further promotes the evolution of the crystal phase. Moreover, the dielectric abnormality appears clearly at ∼120 °C, which is the Curie-transition temperature of BaTiO3. The partly developed tetragonal phase of the ceramics after post-annealing thus leads to the diffuse nature of this dielectric anomaly.