Melting and thermal decomposition of β-Ag6S3O4

It was found that, in air as well as in an inert atmosphere, β-Ag6S3O4 melts incongruently at 390°C. Solid product of the incogruent melting of β-Ag6S3O4 is β-Ag8S4O4, the second phase existing in the Ag2SO4-Ag2S system. β-Ag8S4O4 melts at 400°C. At this temperature and in air the liquid obtained after melting starts decomposing to give metallic silver. In an inert atmosphere or at reduced pressure the liquid starts decomposing at 530°C and the final solid products of this decomposition are silver sulfide and metallic silver, gaseous product is SO2.