Surface-layer effect in CaCu3Ti4O12

Low-frequency (∼100Hz) dielectric properties of CaCu3Ti4O12 were investigated in detail near room temperature. A dielectric relaxation peak was observed at about 250 K with an activation energy of 0.54 eV. This peak can be tuned by annealing treatment in nitrogen and oxygen. The results can be well explained by considering the surface-layer effect. The inhomogeneous distribution of oxygen vacancies leads to the formation of surface layer, resulting in the observed Maxwell–Wagner-type dielectric relaxation.