Effects of Preparation on Giant Dielectric Constant of CaCu_3Ti_4O_(12) Ceramics

CaCu3Ti4O12 ceramics with giant dielectric constant were prepared by the traditional ceramic method, in which the oxide powders were mixed and pre-sintered at 850-950℃, and then sintered at 1050-1090℃, respectively. XRD, SEM and LCR were used to measure the phase structure, the morphology and dielectric properties of the ceramics. The results show that the dielectric constant and the temperature at which the low dielectric constant typically transforms to special high are seriously controlled by the perfection and the defects of grain boundaries of the crystalline. The relaxation temperature of the dipole in the sample pre-sintered at 950℃ and sintered at 1090℃ is 70K lower than that of the dipole in the sample pre-sintered at 880℃ and sintered at 1050℃, and the dielectric constant is 300% enhanced, and simultaneously remains giant in a relative wide temperature range. The better the crystallinity of the ceramic, the faster the transation of the dielectric constant from low to high.