Phasenbeziehungen im System Ag-As-S und thermochemisches Verhalten von Ag₇MX₆-Verbindungen (M = P, As, Sb; X = S, Se) / Phase Relations in the System Ag-As-S and Thermal Behaviour of Ag₇MX₆ Compounds

The phase relations of the ternary system Ag-As-S were established by DTA and X-ray investigations. The quasibinary sections Ag 2 S-Ag 7 AsS 6 and Ag 7 AsS 6 -Ag 3 AsS 3 are described. The system Ag-As-S contains several stable compounds, including Ag 7 AsS 6 as a member of the Argyrodit family. The compounds Ag 7 PS 6 , Ag7AsS 6 , Ag7PSe 6 , Ag7AsSe 6 und AgvSbS 6 were investigated by DSC and high-temperature X-ray methods. All compounds have a phase transformation from space group P2 1 3 to F4̅3m at higher temperatures. Lattice constants and transformation temperatures are given.