Towards enhanced varistor property and lower dielectric loss of CaCu₃Ti₄O₁₂ based ceramics

A novel (1-x)CaCu₃Ti₄O₁₂-xY_2/3Cu₃Ti₄O₁₂ composite ceramic was developed. Two perovskite-like grains, i.e. CaCu₃Ti₄O₁₂ grains of 1-2μm and Y_2/3Cu₃Ti₄O₁₂ grains of 4-6μm, can be both detected in the samples. High Schottcky barrier height and grain boundary resistance were formed via combining these two perovskite-like phases, which plays the critical role on the varistor and dielectric performance. Greatly enhanced nonlinear coefficient of 9.88 and very low dielectric loss of 0.02 can be achieved in the composite ceramics accompanied with the permittivity of ~2000, compared with reported results of 2-6 and 0.05-0.8 for general CaCu₃Ti₄O₁₂ ceramics. This varistor-capacitor multifunctional characteristic makes it a promising material in the field of over voltage protections of electronic devices.