Influence of heterovalent cationic substitution on electrical properties of Ag6+x(P1-xGex)S5I solid solutions

High-quality single crystals of Ag6+x(P1-xGex)S5I (0.25, 0.5, 0.75) solid solutions are grown from the solution-melt by vertical zone crystallization method. In order to study the crystal structure and to establish the mechanism of formation of Ag6+x(P1-xGex)S5I solid solutions as well as to explain the peculiarities of ion transport, the investigation of the single crystals was carried out using XRD analysis by the Rietveld method based on the refined models of initial Ag6PS5I and Ag7Ges5I structures. The measurements of electrical conductivity of single-crystal Ag6+x(P1-xGex)S5I samples was performed using impedance spectroscopy method in frequency range of 1 x 101-2 x 106 Hz and temperature interval of 293-383 K. Ionic and electronic components of electrical conductivity are determined using Nyquist plots. Based on the analysis of compositional dependences, it was found that for solid solutions the maximum of the ionic component of electrical conductivity and the minimum of its activation energy are observed. The features of the ion transport mechanism in Ag6+x(P1-xGex)S5I solid solutions with a heterovalent substitution are explained. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

High-quality single crystals of Ag6+x(P1-xGex)S5I solid solutions were grown by vertical zone crystallization method. The crystal structure and ion transport mechanism were studied using XRD analysis and impedance spectroscopy, showing the peculiarities and maxima of the ionic component in the solid solutions.