Phase relations along the Ag₈GeS₆–[(AgBr)₄·GeS₂] cross-section.
Crystal structure and electric conductivity of Ag₆GeS₄Br₂ in bulk

Chem. Met. Alloys 3 (2010) 161-168

https://doi.org/10.30970/cma3.0153

Mykola V. MOROZ, Pavlo Yu. DEMCHENKO, Lev G. AKSELRUD, Oleksiy G. MYKOLAYCHUK, Roman E. GLADYSHEVSKII

The Т–х-diagram of the Ag₈GeS₆–[(AgBr)₄·GeS₂] polythermal cross-section has been constructed in the range 25-100 mol.%Ag₈GeS₆. The conditions for solid-state synthesis of the Ag₆GeS₄Br₂ quaternary phase have been established. The crystal structure of Ag₆GeS₄Br₂ (Pnma – d ⁸c⁷a, oP96-44.24, Z = 4, a = 6.53892(5), b = 7.72656(5), c = 22.90338(17) Å; X-ray powder diffraction, 820 reflections measured, 58 parameters refined, R_I = 0.0383, R_p = 0.0408, R_wp = 0.0528, χ² = 1.76) is a disordered variant of the structure determined previously on single crystal data. The electrical conductivity of Ag₆GeS₄Br₂ has been measured by the dc probe method between 250 and 410 K. A model for the superionic electrical conduction mechanism is proposed.

Bulk crystal structure of Ag₆GeS₄Br₂ (left) and temperature dependences of the electrical conductivity (right).

Keywords

Ag–Ge–S–Br / Phase diagram / Crystal structure / Electrical conductivity / Superionics