Raman, Dielectric and AC-conductivity Behavior of Dy_2O_3 Contained K_(0.5)Na_(0.5)NbO_3 Ceramics

摘要

Lead-free piezoelectric (K_(0.5)Na_(0.5))NbO_3+ x wt% Dy_2O_3 (x = 0 - 1.5) (KNND) ceramics have been prepared by solid state reaction method. The effect of Dy_2O_3 on the dielectric and electrical conductivity responses of KNN ceramics were investigated in a broad temperature (from 133 K to 673 K) and frequency (10~6 Hz to 10~8 Hz) range. Temperature dependent dielectric analysis revealed that the polymorphic phase transition orthorhombic to tetragonal transition temperature (T_(O-T)) shifted from 199°C to room temperature with enhanced dielectric permittivity (ε' = 994) with the addition of Dy_2O_3. The effect of Dy_2O_3 on structural properties of KNND ceramics are analyzed interms of changes in the internal modes of NbO_6 octahedra by using Raman spectroscopy. Temperature dependent (133 K - 306 K) AC-conductivity follows the variable range hopping mechanism in different temperature regimes.