Phase formation, microstructure, and electrical properties of lead-free BNBLT-CZ ceramics synthesized via the solid-state combustion technique

Lead-free 1-x(Bi_0.47Na_0.47Ba_0.06)_0.95La_0.05TiO₃-xCaZrO₃ (BNBLT-xCZ) ceramics with x = 0, 0.01, 0.02, 0.03, and 0.04 were synthesized by the solid-state combustion technique with a calcination temperature of 750 °C for 2 h and a sintering temperature of 1150 °C for 2 h. The effect of CZ substitution on the phase formation, microstructure, and electrical and energy-storage properties of the BNBLT-xCZ ceramics was investigated. The BNBLT-xCZ ceramics showed coexisting rhombohedral (R) and tetragonal (T) phases for all compositions. The T phase tended to increase and then rapidly decreased at x = 0.03, as verified by Rietveld refinement analysis. The average grain size decreased from 1.13 ± 0.37 to 0.78 ± 0.22 μm when x increased from 0 to 0.04. The measured density was in the range of 5.45 ± 0.03–5.67 ± 0.06 g/cm³. The maximum dielectric constant (ε_m), remanent polarization (P_r), and coercive field (E_c) decreased with increased CZ content. A significant decrease in the maximum polarization (P_max) was obtained with CZ ≥ 0.03. The results of impedance spectroscopy demonstrated that the bulk response in resistivity decreased as CZ content increased. Under an electric field of 100 kV/cm, the BNBLT-0.03CZ ceramic exhibited a maximum energy-storage efficiency (η) of 80.3% and a high energy-storage density (W) of 0.92 J/cm³.