The effects of Si-doping on the properties of CaCu3Ti4O12 ceramics

CaCu₃Ti₄O₁₂ (CCTO) ceramics as a dielectric material are of potential applications in capacitors and memory devices, however, how to further improve the dielectric properties of CCTO ceramics is still a challenge. The dielectric behavior of this material can be manipulated via the modification in composition, and Si as a glass phase should have an impact on the properties of CCTO ceramics, this work investigated the effects of Si-doping on CaCu₃Ti₄O₁₂ with the aim of improving dielectric characteristics. CaCu₃Ti₄O₁₂ ceramics of various Si-doping concentrations were synthesized by solid state reaction method at 1050 C. The microstructure and the dielectric properties of Si-doped and undoped CaCu₃Ti₄O₁₂ were studied. It is found that the added silicon can be incorporated into the structure of CaCu₃Ti₄O₁₂, a certain amount of Si-doping would facilitate the grain growth, promote the precipitation of intergranular phase, and improve the compactness and homogeneity of CaCu₃Ti₄O₁₂ ceramics. Si-doped CaCu₃Ti₄O₁₂ samples show significantly higher dielectric constant, accompanied by larger dielectric loss. The temperature dependence of dielectric permittivity ε" for various frequencies shows three successive sets of peaks attributed to intrinsic relaxation polarization processes, suggesting that Si-doping has little influence on the relaxation mechanism of CaCu₃Ti₄O₁₂ ceramics.