Investigation of the conductivity of Na2SO4–PbTiO3 composite electrolyte system: Non linear electrical behavior at Curie temperature of the dispersoid
Abstract The effect of dielectric constant of the PbTiO 3 dispersoid on the conductivity of Na 2 SO 4 has been probed. At the Curie temperature, 490 °C, PbTiO 3 undergoes ferroelectric to paraelectric phase transition followed by a sharp change in the dielectric constant. The Na 2 SO 4 –PbTiO 3 composites have been prepared at two different temperatures, namely 600 and 900 °C. Compositions containing 5, 10, 20, 30, 40, 50 m% PbTiO 3 have been investigated using Impedance Spectroscopy, Differential Scanning Calorimetry (DSC), X-ray diffraction (XRD) and Rietveld analysis. The series of compositions prepared at 900 °C exhibit a maxima in the conductivity for 20 m% PbTiO 3 . The composites prepared at 600 °C exhibit a peak in the conductivity at 20 m% PbTiO 3 in addition to the percolation threshold at 40 m% PbTiO 3 . The enhancement in the conductivity by a factor of 40 at 300 °C has been observed for the system prepared at 600 °C while an enhancement in the conductivity by a factor of 8 at 300 °C has been observed for the system prepared at 900 °C. Further, the transition temperature of Na 2 SO 4 remains unaltered for both series. A slight nonlinearity has been observed in the vicinity of the transition temperature of the dispersoid.