Grain-Size Effect on Electrical Properties of (Bi 1/2 K 1/2 )TiO 3 Ceramics

In this study, Bi 2 O 3 -doped bismuth potassium titanate, (Bi 1/2 K 1/2 )TiO 3 , (abbreviated to BKT-Bi x ; x =0, 0.1, 0.2, 0.4, and 0.6 wt %) ceramics were fabricated by hot-pressing method, and its electrical properties were investigated in detail. Moreover, BKT-Bi0.6 was annealed at 1040 °C for 4–20 h to develop grains [abbreviated to BKT-Bi0.6( y h); y =4, 10, and 20]. The ferroelectric properties were improved by grain growth, and the remanent polarization, P r , of BKT-Bi0.6(10 h) was 27.6 µC/cm 2 . The piezoelectric properties were improved by field cooling method, and the electromechanical coupling factor, k 33 , and piezoelectric constant, d 33 , of BKT-Bi0.6(10 h) improved up to 0.40 and 101 pC/N, respectively. Moreover, the temperature dependences of piezoelectric properties were measured, and piezoelectricity disappeared at 280 °C for BKT-Bi0.6(10 h).