Correlation between dielectric properties and sintering temperatures of polycrystalline CaCu3Ti4O12

Dielectric properties of polycrystalline CaCu₃Ti₄O₁₂ (CCTO) pellets sintered in the temperature range 1000-1200°C were evaluated with impedance spectroscopy at frequency range of 10² to 10⁷ Hz from 90 K to 294 K. A correlation has been established between the pair values of low frequency limit dielectric constant and the total resistivity and the sintering temperature. For example, the sample sintered at 1100°C demonstrates higher value of low frequency limit dielectric constant and lower value of total resistivity, while the sample sintered at 1000°C demonstrates lower values of low frequency limit dielectric constant and higher value of total resistivity. This correlation has been successfully explained by relating with the difference in grain size and grain volume resistivities of these two polycrystalline CCTO samples. Further, it is suggested that donor doping of oxygen vacancies Vo\´ and Vo" may be the reason to cause the difference in the grain volume resistivities of these two samples.