Sulfur-selenium isomorphous substitution in the AgAu(S,Se) series

Results of the studies evidence the existence of continuous solid solution of the AgAuS-AgAuSe series. As a result of the partial isomorphous replacement Se → S, the unit cell parameters of petrovskaite-like type (R3¯m) phases are slightly increased compared to AgAuS. The phases AgAuS1-xSex at 0.5 < х ≤ 1 are, most likely, metastable, their instability drastically increasing with the growing content of selenium. The phases partly decompose to form a fischesserite-like phase Au3Au(Se,S)2 or fischesserite (Au3AuSe2) (at x = 1), high-fineness Au-Ag alloy, S,Se phase or Se (at x = 1) and β-(Au,Ag) (Se,S) (at x = 0.875 and 1). Gold selenide AuSe showed isomorphism Se → S to 0.17 mol fraction of sulfur and Au → Ag - to 0.1 mol fraction of silver. The content of AgAuSe phase, synthesized under different heating, annealing and cooling conditions, was the highest in the experiment with rapid cooling from 1050 °C without annealing. The existence of phase AgAuSe in natural systems is likely to be very problematic.