The Relationship Between Phase Structure and Electrical Properties in (1 −  x )( Bi _0.5 Na _0.5 TiO ₃ – Ba _0.5 K _0.5 TiO ₃ – BaTiO ₃ )‐ x K _0.5 Na _0.5 NbO ₃ Quaternary Lead‐Free Piezoelectric Ceramics

Abstract

(1 − x )(0.85 Bi 0.5 Na 0.5 TiO 3 –0.11 Ba 0.5 K 0.5 TiO 3 –0.04 BaTiO 3 )‐ x K 0.5 Na 0.5 NbO 3 lead‐free piezoelectric ceramics with x = 0.00, 0.02, 0.03, 0.04, 0.05, and 0.10 were prepared by a conventional solid state method. A coexistence of rhombohedral (R) and tetragonal (T) phases was found in the system, which tended to evolve into pseudocubic symmetry when x increases. The x = 0.04 sample exhibited improved electrical properties: the dielectric constant ε r = 1900 with the low loss tangents 0.06, the S max / E max of ~400 and ~460 pm/V under unipolar and bipolar electric field, respectively. Meanwhile, piezoelectric constant d 33 still maintained ~160 pC/N. These could be owed to the formation of polar nanoregions for relaxor phase.