Piezoelectric, ferroelectric and dielectric properties of La2O3-doped (Bi0.5Na0.5)0.94Ba0.06TiO3 lead-free ceramics

La2O3 (0-0.8 wt.%)-doped (Bi0.5Na0.5)(0.94)Ba0.06TiO3 (abbreviated as BNBT6) lead-free piezoelectric ceramics were synthesized by conventional solid-state reaction. The influences of La2O3 on the microstructure, the dielectric, ferroelectric and piezoelectric properties of the composites were investigated. X-ray diffraction (XRD) patterns indicate that 0.2-0.8 wt.% of La2O3 has diffused into the lattice of BNBT6 ceramics. Consequently, a pure perovskite phase is formed. SEM images show that the microstructure of the ceramics is changed with the addition of a small amount of La2O3. The temperature dependence of the relative dielectric constant shows that Curie point decreases with the increase of La2O3. At room temperature, the ceramics doped with 0.6 wt.% La2O3 show superior performance with high piezoelectric constant (d(33) = 167 pC/N), high planar electromechanical coupling factor (k(p) = 0.30), high mechanical quality factor (Q(m) = 118), high relative dielectric constant (epsilon(r)= 1470) and lower dissipation factor (tan delta = 0.056) at a frequency of 10 kHz. (C) 2009 Elsevier Ltd. All rights reserved.