Enhanced ferroelectric and energy-storage properties of Nb-doped 0.94Na0.5Bi0.5TiO3-0.06BaTiO3 ceramics prepared by a multi-ionic sol-gel method

Abstract Lead-free ferroelectric Na 0.5 Bi 0.5 TiO 3 (NBT), 0.94Na 0.5 Bi 0.5 TiO 3 -0.06BaTiO 3 (NBT-6BT) and (Na 0.5 Bi 0.5 ) 0.94 Ba 0.06 (Nb 0.05 Ti 0.95 )O 3 (Nb-NBBT6) ceramics were synthesized via a multi-ionic sol-gel method process. The effects of Nb on the structural, dielectric and ferroelectric properties were studied. Doped Nb ions distributed uniformly in the Nb-NBBT6 ceramics and shrank the grain sizes of Nb-NBBT6. All NBT, NBT-6BT and Nb-NBBT6 ceramics consisted of the rhombohedral phase and the tetragonal phase according to XRD Rietveld refinements. The dielectric constants of the Nb-NBBT6 ceramics were improved compared to NBT and NBT-6BT below 200 °C. The introduction of Nb ions enhanced the dielectric stability, and the temperature difference between two dielectric peaks increased from 153 °C for NBT to 197 °C for Nb-NBBT6. The remnant polarization ( P r ) of Nb-NBBT6 ceramics decreased, but the reduced E c of 7.01 kV/cm and the maximum polarization of 40.79 μC/cm 2 (90 kV/cm) revealed the enhanced ferroelectric property. The temperature-dependent ferroelectric hysteresis loops of Nb-NBBT6 ceramics (65–150 °C) exhibited the largest energy-storage density ( W ) of 0.399 J/cm 3 at 90 °C.