Enhanced energy-storage properties of 0.89Bi0.5Na0.5TiO3–0.06BaTiO3–0.05K0.5Na0.5NbO3 lead-free anti-ferroelectric ceramics by two-step sintering method

• Lead-free 0.89BNT–0.06BT–0.05KNN AFE ceramics were prepared by pressureless two-step sintering method.
• The energy-storage density and AFE properties were significantly enhanced by two-step sintering method.
• The ceramics by two-step sintering method had smaller grain size and more uniform microstructure than those of the ceramics by single-step sintering method.

This work compared the effects of different sintering methods on the microstructure and anti-ferroelectric properties of lead-free 0.89Bi0.5Na0.5TiO3–0.06BaTiO3–0.05K0.5Na0.5NbO3 ternary system ceramics. The ceramics by two-step sintering method had smaller grain size and more uniform microstructure than those of the ceramics by single-step sintering method. The mechanism of grain growth in different sintering methods is discussed. The ceramics by two-step sintering method exhibited better anti-ferroelectricties than those of the ceramics by single-step sintering method. The polarization hysteresis (P–E) loop showed optimum electrical performances with a low remanent polarization (Pr=5.4 μC/cm2) and a coercive field (Ec=8.2 kV/cm), and the energy density (W) reached 0.90 J/cm3 at 10 Hz. The storage capacity is three times that of the single-step sintering ceramics.