Abstract:
(Bi0.5Na0.5)0.94Ba0.06TiO3 lead-free ceramics were prepared via the cold sintering followed by post-annealing method. Effects of annealing temperatures on phase, microstructure, piezoelectric, dielectric, and ferroelectric properties of the ceramics were studied in detail. All post-annealed ceramics exhibit pure perovskite structure. The relative density of the cold sintered pellet is 71.8%. The relative densities of the post-annealed ceramics are 81.7%~97.1% as the annealing temperatures are between 1 000 and 1 100 ℃. The average grain sizes of the post-annealed ceramics are 600~800 nm. All ceramics show dielectric diffuse factor of 1.85~1.96. The depolarization temperatures of the ceramics annealed at 1 025, 1 050, 1 075 and 1 100 ℃ are 130, 137, 135 and 123 ℃, respectively. The ceramic annealed at 1 075 ℃ has maximum polarization and remnant polarization of 60.9μC/cm2 and 51.8μC/cm2, respectively. Compared to the breakdown strength (<75 kv/cm) of the (bi0.5na0.5)0.94ba0.06tio3 ceramics sintered via a conventional solid-state reaction method, the breakdown strength of the present ceramics are significantly improved (>100 kV/cm). The piezoelectric constant d33 of the ceramics increases from 52±7 pC/N to 101±2 pC/N as the annealing temperatures increase from 1 000 ℃ to 1 100 ℃. The study shows that cold sintering followed by post-annealing is successful in preparing (Bi0.5Na0.5)0.94Ba0.06TiO3 ceramics with excellent electrical properties.
