Effects of preparation on giant dielectric constant of CaCu3Ti4O12 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 similar to 950 degrees C, and then sintered at 1050 similar to 1090 degrees C, 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 degrees C and sintered at 1090 degrees C is 70K lower than that of the dipole in the sample pre-sintered at 880 degrees C and sintered at 1050 degrees C, 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.