Dielectric and Impedance Studies on (K0.5Na0.5)NbO3-Based Ceramics

Polycrystalline, lead-free (K0.5Na0.5)NbO3-based ceramics were synthesized using solid-state reaction method. The microstructure, dielectric and impedance characteristics of the ceramics were studied. The results showed that the obtained doped ceramic had a pure perovskite structure with pseudo-cubic phase. Some dielectric anomalies were observed at about 200 degrees C, and 500 degrees C for the ceramics, respectively. With the increase of BaBiO3 doping content, the dielectric constant-temperature transition peak value became weaker. The activation energy of conductivity is found to be closely related to the frequency. The activation energy obtained from the dielectric relaxation data was attributed to oxygen vacancies. The calculated activation energies at 10 kHz for the temperature range (200-500 degrees C) and (200-350 degrees C) and (350-500 degrees C) are 0.657, 0.542 and 0.350 eV, respectively.