High permittivity and low dielectric loss of Na0.5Bi0.5−xLaxCu3Ti4O12 ceramics

The phase structure, microstructure and dielectric properties of Na0.5Bi0.5−xLaxCu3Ti4O12 (NBLCTO) ceramics were investigated. La3+ substitution had a great influence on the phase structure and dielectric properties. The results showed that the pure phase could be more easily obtained when substituting La3+ for Bi3+. Under the same processing condition (970 °C for 7.5 h) and measuring condition (10 kHz around room temperature), NBLCTO ceramics with x = 0.10 possessed the highest permittivity (1.02 × 104) and lowest dielectric loss (0.022). The obtained NBLCTO ceramics with x = 0.10 also had good frequency stability and good temperature stability (−1.87% to +3.27%) from −60 °C to 120 °C at both 1 and 10 kHz. Complex impedance results revealed that the grain resistance Rg was 7.18 Ω cm and the grain boundary resistance Rgb was 1.19 × 106 Ω cm.