Microstructure and enhanced dielectric properties of yttrium and zirconium co-doped CaCu3Ti4O12 ceramics

CaCu3Ti4O12 (CCTO) ceramics doped with Y2O3, ZrO2, and (Y2O3+ZrO2) were prepared by the citrate-nitrate combustion derived powders in order to investigate the effect of dopants on the microstructure and electrical properties. The results showed that giant dielectric response was enhanced by co-doping of Y3+ and Zr4+ ions at the Ti site. Y2O3 and ZrO2 additive can inhibit the grain growth. Compared with other samples, (Y2O3+ZrO2) co-doped ceramics exhibit a dense and homogenous fine-grained microstructure. A much better temperature and frequency stability of dielectric properties were realized in these ceramics. The dielectric loss (tan δ) < 0.05 in the frequency range of 200 Hz-60 kHz at room temperature, and in the temperature range of 15-72 °C at 10 kHz was successfully accomplished in (Y2O3+ZrO2) co-doped CCTO ceramics. Low tan δ ∼0.039 and high dielectric constant (εr ∼10196) were observed at room temperature and 10 kHz for the above ceramic samples, and the characteristic frequency shifts to higher frequency with increasing measuring temperature. The present results indicate that (Y2O3+ZrO2) co-doping may improve the dielectric properties and increase the grain boundary resistance of CCTO.