Structure and dielectric properties of Na and Ta doped CaCu3Ti4O12

New ceramic compositions based on Na and Ta doped CaCu₃Ti₄O₁₂ (CCTO) solid solutions were obtained. The synthesis conditions, parameters of crystal structure and low frequency dielectric properties depending on Na and Ta concentrations were investigated. The solid solutions were obtained by substitution of Ca and Ti in the CCTO structure with Na and Ta, respectively, according to the formula Ca_1-xNa_xCu₃Ti_4-xTa_xO₁₂. The substitution scheme occurs in a whole range of x from 0 to 1. The sintering temperature of Na and Ta doped CCTO ceramics with 90-95% of theoretical density is lower than of undoped CCTO. 1 kHz dielectric permittivity of Ca_1-xNa_xCu₃Ti_4-xTa_xO₁₂ ceramics depends on x and varies from 2600 to 9700. Dielectric losses tangent is around 0.1.