Influence of annealing environments on the conduction behaviour of KNN-based ceramics

The electrical conduction behaviour of the lead-free (1-x)K0.5Na0.5Nb0.95Sb0.05O3-xBi(0.5)Na(0.41)K(0.09)ZrO(3) (x = 0.05) ceramics annealed in air, oxygen, and argon environments at various temperatures was investigated. Post-sintering annealing in different atmospheres affected the temperature of dielectric phase transition and electrical conductivity values significantly. The ceramic sample annealed in an oxygen environment showed the lowest conductivity for grain (sigma(g) similar to 1.22 x 10(-5) S/m) and grain boundary (sigma(gb) similar to 1.56 x 10(-6) S/m) regions at 250 degrees C which is due to the reduction in oxygen vacancy defects. The activation energy E-a for DC conduction in this sample obeyed the Arrhenius relation and was found to be similar to 0.99 +/- 0.03 eV. An additional anomaly observed at T similar to 250 degrees C dielectrics vs. temperature plots for the as-sintered and argon-annealed samples is ascribed to defect relaxation, which was inconspicuous in the samples annealed in air and oxygen. In addition, the in-situ impedance measurement was performed to analyze the impact of argon atmosphere on the electrical conductivity of the O-2-annealed samples with high-temperature electrode curing.

Automated summary

The electrical conduction behavior of lead-free BiZnNbO ceramics annealed in different atmospheres was studied, with the sample annealed in oxygen environment showing the lowest conductivity due to reduced oxygen vacancy defects. An anomaly observed at 250 degrees Celsius in dielectric plots for certain samples was attributed to defect relaxation.