High dielectric permittivity and low dielectric loss in sol-gel derived Zn doped CaCu3Ti4O12 thin films

Zn-doped CaCu3−xZnxTi4O12 high dielectric films with low dielectric loss were prepared by the sol-gel method; their crystalline structure, microstructure and electrical properties were investigated. A new method, XRD complemented by CLSM, was used to prove the presence of ZnO in CCZTO films, indicating the existence of the Cu2+ vacancy which influenced the electrical properties directly. The average grain size enlarged with the increased Zn doping amounts. All the samples showed strong non-ohmic properties. Higher nonlinear coefficient and lower leakage current depended on the increased VCu″ concentration. It is significant that the Zn doping effectively reduced the dielectric loss in the low and medium frequency region even though the Zn doping led to the dielectric constant decreased compared to the pure CCTO film. At x = 0.20, the minimum dielectric loss of 0.015 can be observed around 22 000 Hz, which is the best-reported value in CCTO-based material.