SYNTHESIS, PIEZOELECTRIC, DIELECTRIC AND CONDUCTIVITY STUDIES ON Dy2O3 SUBSTITUTED (Bi0.94Na0.94)(0.5)Ba0.06TiO3 CERAMICS

Polycrystalline (Bi0.94-xDyxNa0.94)(0.5)Ba0.06TiO3 ceramics (x = 0, 0.04, and 0.08, designated as BNBT6, BNBT6: 4Dy and BNBT6: 8Dy, respectively) were prepared by conventional high temperature sintering method. The X-ray diffraction patterns show pure perovskite structure with no secondary phases. Lattice parameters and unit cell volumes have decreased due to Dy2O3 substitution. SEM micrographs revealed denser samples (rho(rel) > 97%) with uniformly distributed grain sizes. The room temperature piezoelectric properties of Dy2O3 substituted sample at x = 0.04 were relatively higher: d(33) = 147 pC/ N, k(p) = 28% and Q(m) = 128. The samples exhibited infinitesimal change in thickness (approximate to 15 nm) to an applied voltage of 100 V, which could be utilized in actuator applications. Relaxor behavior and broad dielectric maxima with diffuse phase transition were observed. The value of RT dielectric constant has increased while dielectric loss was decreased due to Dy2O3 substitution. Conductivity in the materials obeys Jonscher's universal power law. The conductivity in the low frequency region is associated with short range translational hopping while it is associated with the reorientational hopping in the high frequency region. The charge carrier concentration term remained constant over the entire temperature range of (30-500 degrees C).