The sintering behavior and physical properties of Li₂CO₃-doped Bi_0.5(Na_0.8K_0.2)_0.5TiO₃ lead-free ceramics

Abstract

Abstract In this study, Li 2 CO 3 -doped Bi 0.5 (Na 0.8 K 0.2 ) 0.5 TiO 3 (BNKT) ceramics were fabricated via the conventional solid-state reaction using ultrasound waves for preliminary milling. The milling time was shortened from 20 h to 1 h with ball milling. The phase structure of BNKT investigated by X-ray diffraction showed a single perovskite phase. With increasing Li 2 CO 3 content, the phase structure of the ceramics changed from rhombohedral to tetragonal. At a sintering temperature of 1100 °C and Li 2 CO 3 content of 0.4 wt.%, the best physical properties of the ceramics, such as density ( ρ ), 5.9 g cm −3 ; electromechanical coupling factors ( k p ), 0.32; ( k t ), 0.29; remanent polarization ( P r ), 12.0 μC cm −2 ; dielectric constant ( ∊ r ), 1 191; and highest dielectric constant ( ∊ max ), 5 800, were obtained.