Modified giant dielectric properties of samarium doped CaCu3Ti4O12 ceramics

Effects of Sm3+ substitution on the microstructure and dielectric properties of CaCu3Ti4O12 ceramics were investigated. The grain size of CaCu3Ti4O12 ceramics was greatly decreased by doping with Sm3+, resulting from the ability of Sm3+ to inhibit the grain growth rate. This result can cause a decrease in the dielectric constant (ɛ′) and loss tangent (tan δ) of CaCu3Ti4O12 ceramics. Interestingly, high dielectric permittivity (ɛ′ ∼ 10,863) and low loss tangent (tan δ ∼ 0.043 at 20 °C and 1 kHz) were observed in the Ca0.925Sm0.05Cu3Ti4O12 ceramic. Nonlinear electrical properties of CaCu3Ti4O12 ceramics were modified by doping with Sm3+. The dielectric relaxation behavior of Sm-doped CaCu3Ti4O12 ceramics can be well ascribed based on the internal barrier layer capacitor model of Schottky barriers at the grain boundaries.