Estimation of charge-carrier concentration and ac conductivity scaling properties near the V-I phase transition of polycrystalline Na2SO4 -: art. no. 174303

The conductivity spectra of polycrystalline Na2SO4 have been investigated in the frequency range 42 Hz-1 MHz at different temperatures below and above the V-I phase transition temperature. The conductivity data have been analyzed using Almond-West formalism. The dc conductivity, the hopping frequency of the charge carriers, and their respective activation energies have been obtained from the analysis of the ac conductivity data, and the concentration of charge carriers was calculated at different temperatures. The power-law exponent n of the conductivity spectra has average values of 0.43 and 0.61 in phases V and I, respectively, which indicates different conduction properties in the two phases. Moreover, scaling of the conductivity spectra at the low- and high-temperature phases was performed in accord with Ghosh's scaling approach. It is found that the scaling properties depend on the structure of the investigated material.