Dielectric properites of Al-doped CaCu3Ti4O12 ceramics by coprecipitation method

Undoped and Al-doped CaCu₃Ti₄O₁₂ Ceramics (CCTO) ceramics were prepared by the coprecipitation method, and the electric and dielectric properties were investigated. The concentration of Al-doped in CCTO influenced the electric and dielectric properties. Through adjusting the concentration of Al-doped, we obtained polycrystalline ceramics samples with the improved properties of dielectric loss and high dielectric permittivity over the wide frequency range. The results indicated that a high dielectric constant and low dielectric loss can be achieved by Al³⁺ substitution for Ti⁴⁺, because the Al-doped CCTO could enhanced the grain boundary resistivity, and the optimum doping concentration is about x=0.3. With x=0.3 Al doping, the dielectric constant was 16000 at 1 kHz and the loss value was below 0.1 over the frequency range of 10² Hz to 10⁴ Hz.