Enhancement of ionic conductivity in the composite solid electrolyte system: TlI–Al2O3

Abstract

This paper reports the heterogeneously doped alumina (Al2O3) on the ionic conductivity of thallium iodide. Composite materials of formula (1 − x) TlI–xAl2O3, x = 0–0.7 have been prepared and studied by X-ray diffraction, differential scanning calorimetry, and electrical conductivity. X-ray diffraction and differential scanning calorimetry proved the formation of composite in this binary system. The maximum enhancement observed is about three orders of magnitude with respect to the host material. The enhancement of electrical conductivity in comparison with pure thallium iodide can be interpreted with the space charge layer model. Moreover, the increased content of alumina in the system leads to the disappearance of phase transition β–α thallium iodide, which is usually observed in the pure compound. This behavior was explained by stabilizing effect of β-phase at high temperatures and suppression of α-phase at higher contents of alumina.