Effect of Pb addition on dielectric relaxation in Se80In20 glassy system

Dielectric properties of Se80In20−xPbx (x = 0, 5, 10 and 15) chalcogenide glassy system are studied employing impedance spectroscopic technique in the frequency range 100 Hz–1 MHz and in the temperature range 313–383 K. It is found that the dielectric constant ε′and dielectric loss factor ε″ both are dependent on frequency and temperature. The activation energy is also evaluated from the Arrhenius plot of the DC conductivity. All the above parameters show a reversal trends at 5 at wt.% of Pb. Also, anomalous behavior of ε′ at low frequencies at all measured temperatures is observed for 15 at wt.% of Pb. This may be due to PbSe polaron formation, which is confirmed in Raman spectra of the investigated system.

► Composition Se80In5Pb15 shows anomalous dielectric response. ► This anomaly is explained in terms of Pb–Se polaron formation. ► Formation of Pb–Se polaron is also confirmed in Raman study of Se80In20−xPbx. ► Space charge/orientational polarizations contribute to total dielectric response. ► Frequency dependent total conductivity is the sum of DC and AC conductivities.