Effect of nanocrystalline structures on the large strain of LiNbO3 doped (Bi0.5Na0.5)TiO3-BaTiO3 materials

0.025LiNbO(3) (LN) modified 0.94Bi(0.5)Na(0.5)TiO(3)-0.06BaTiO(3) (BNT-BT) ceramics with micrometer-size and nanometer-size grains have been prepared by conventional soild state sintering (CS) and spark plasma sintering (SPS) processes, respectively. Comparing with the CS sample, the SPS sample presents a smaller dielectric constant but a larger piezoelectric constant and a lower triggering electric field. At room temperature, the maximum strain of the SPS ceramic is up to 0.64% at 50 kV/cm electric field, the corresponding d(*)33 reaches the maximum value of 1280 pm/V, which is much higher than that of the CS ceramic and also the ever reported lead-free polycrystalline ceramics. Morever, the strain hysteresis of the SPS ceramic is only 19.5%, while the ceramics prepared by CS process show a much larger strain hysteresis of 58.5%. Thus, the LN doped BNT-BT ceramics with nano grains can achieve maximum strain in designing high-precision devices and actuators with small hysteresis. (C) 2018 Elsevier B.V. All rights reserved.