Maxwell–Wagner relaxation in CaCu3Ti4O12/Ag composites

CaCu3Ti4O12/Ag composites with different Ag weight fractions were prepared by sintering thoroughly mixed CaCu3Ti4O12 and Ag2O powders at 1050 °C in air. The samples were found to consist of Ag-deficient insulating surface layers and Ag-rich more conductive inner parts. Dielectric measurements reveal that, apart from the distinct dielectric features for pure CaCu3Ti4O12, another dielectric relaxation appears near room temperature. This relaxation has been interpreted based on the Maxwell–Wagner model due to discontinuity of the charge concentration across the interface between the surface and inner layers.