Manufacture and dielectric properties of X9R Bi-based lead-free multilayer ceramic capacitors with AgPd inner electrodes

In this paper, 0.6(Na_0.5Bi_0.5)TiO₃–0.4NaNbO₃(0.6NBT–0.4NN) was synthesized by solid state reaction method. The homogenous green ceramic sheets with high density were produced by tape casting according to suitable casting parameters. Embryos of multilayered ceramic capacitors (MLCC) had been fabricated by punching, screen printing, stacking, laminating and cutting processes. And then after burning out and sintering at different conditions, the cross-sectional microstructures of components were compared. Differential scanning calorimetric analysis and the thermo-gravimetric analysis of green devices were carried out to analyze the effects of different sintering procedures on MLCCs. The dielectric properties and polarization loops of the MLCCs were investigated with dielectric constant (800–895), dielectric loss (0.004–0.007) and capacitance variation ΔC/C < 11 % in the temperature range of −55 to 205 °C, which satisfied X9R in the Electronic Industries Association standard. The breakdown strength of the capacitor was 260 kV/cm. The resistance of the capacitor was measured to be 1.873 × 10¹¹ Ω. These properties of the 0.6NBT–0.4NN ceramic capacitor indicated the potential dielectric materials for the application of MLCCs at the high temperature.