Abstract:
Charge transport in (TlGaSe$_{2}$)$_{1-x}$(TlInS$_{2}$)$_{x}$ solid solutions in the frequency range of 20–10$^6$ Hz before and after $\gamma$ irradiation is studied using impedance-spectroscopy methods. The relaxation character of the permittivity dispersion and the nature of the dielectric loss are established. The frequency dependence of the dissipation factor tan$\delta$ in the crystals of the (TlGaSe$_{2}$)$_{1-x}$(TlInS$_{2}$)$_{x}$ solid solutions is caused not only by relaxation polarization, but also by reach-through conductivity. The relaxation times are found to be $\tau$ = 10$^{-3}$ s. It is determined that, in the frequency range of 10$^5$ – 5 $\times$ 10$^5$ Hz, the electrical conductivity obeys the regularity $\sigma\sim f^S$ (0.1 $\le$ S $\le$ 1.0), which is indicative of the conductivity over localized states. It is shown that a further increase in the frequency leads to an increase in the ionic conductivity and transition of the system to the superionic state.
Keywords:solid solutions, permittivity, relaxation time, dielectric loss, conductivity, impedance.