Phase Formation, Morphology and Electrical Properties of Lead-Free BNBLT-xBSN Ceramics Synthesized via the Solid-State Combustion Technique

Lead-free 1-x(Bi0.47Na0.47Ba0.06)0.95La0.05TiO3-xBa(Sn0.70Nb0.24)O3 (BNBLT-xBSN) ceramics with x = 0, 0.01, 0.02, 0.03 and 0.04 mol.% 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 BSN substitution on the phase formation, microstructure, dielectric, ferroelectric and energy storage properties of the BNBLT ceramics was investigated. With the substitution of BSN, the coexisting rhombohedral (R) and tetragonal (T) phases transformed into coexisting R and cubic (C) phase, verified by Rietveld refinement. The C phase increased with increased BSN content. The average grain size decreased from 1.14 to 0.89 µm when x increased to 0.03 and then increased to 0.96 µm. The measured density and maximum dielectric constant (ε m) tended to increase from 5.44 to 5.87 g/cm³ and 1800 to 1942 when x increased to 0.03, then decreased to 5.25 g/cm³ and 1501, respectively. The remanent polarization (P r) and coercive field (E c) decreased when x increased to 0.03. The 0.97BNBLT-0.03BSN ceramic exhibited the lowest energy loss density (W loss ∼ 0.10 J/cm³) and the highest energy-storage efficiency (η ∼ 77.3%) measured under an electric field of 70 kV/cm.