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

• Published in: Journal of alloys and compounds Vol. 873; p. 159784
• Main Authors: Studenyak, I.P., Pogodin, A.I., Filep, M.J., Symkanych, O.I., Babuka, T.Y., Kokhan, O.P., Kúš, P.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 25.08.2021; Elsevier BV
• Subjects: Argyrodites; Crystal structure; Crystallization; Electrical conductivity; Electrical properties; Electrical resistivity; Electronic components; Frequency ranges; Ion transport; Ions; Nyquist plots; Rietveld method; Single crystals; Solid solutions; Substitutes; Superionic conductors; Single crystals; Argyrodites; Electrical conductivity; Solid solutions; Superionic conductors; Crystal structure
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2021.159784

•Crystals of Ag6+x(P1−xGex)S5I solid solutions are grown from the solution–melt.•Electrical conductivity was measured by means of impedance spectroscopy.•The ion transport mechanism in Ag6+x(P1−xGex)S5I solid solutions was studied. [Display omitted] 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 × 101–2 × 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.