Dielectric properties and electrical conduction of La₂O ₃-doped (Bi_0.5Na_0.5)_0.94Ba _0.06TiO₃ ceramics

La₂O₃ (2 wt%)-doped (Bi_0.5Na _0.5)_0.94Ba_0.06TiO₃ (abbreviated as BNBT6) lead-free piezoelectric ceramics were synthesized by conventional solid-state reaction. X-ray diffraction (XRD) patterns indicated that La ₂O₃ has diffused into the lattice of BNBT6 ceramics and formed a solid solution with a pure perovskite structure. Addition of La ₂O₃ decreased the piezoelectric properties and electrical conductivity. It was used to study the electrical conductivity of the La ₂O₃-doped BNBT6 lead-free piezoelectric ceramics combined with electrical modulus and impedance plots at the temperature range over 788-873 K. The values of activation energy derived from the electrical impedance and modulus were found to be 0.51 and 0.50 eV, respectively. The discrepancy between activation energy of relaxation frequency and the activation energy (0.25 eV) of dc electrical conductivity might have been due to a short-range migration or hopping of single ionized oxygen vacancy and a long-range migration or hopping of charge carriers over the whole disordered system, respectively.