Synthesis and characterisation of new potassium-containing argyrodite-type compounds

Abstract

Potassium halogen thiophosphates K₆PS₅Br and K₆PS₅Cl, as well as halogen-free K₇PS₆ compound, were synthesized using the two-step technique from elemental substances as well as potassium halides. The elemental composition of the obtained samples was determined using energy-dispersive X-ray spectroscopy. Raman spectra of K₆PS₅Br and K₆PS₅Cl show themselves to be very similar to those of chemically related Cu₆PS₅Br and Cu₆PS₅Cl argyrodite crystals. The much richer spectra of K₆PS₅Br and K₆PS₅Cl, as well as K₇PS₆, however, reveal that their structure most likely differs from the cubic structure of Cu₆PS₅Br and Cu₆PS₅Cl argyrodites.