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

Abstract 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. Highlights • Nano-grain 0.975(0.94BNT-0.06BT)-0.025 LiNbO 3 ceramic was prepared by SPS. • A maximum strain of 0.64% at 50 kV/cm and a d 33 ∗ of 1280 pm/V were obtained. • Much lower strain hysteresis of only 19.5% was found in the nano-grain ceramic. • The improved piezoelectric performance is related to fine core-shell structures. [ABSTRACT FROM AUTHOR]