Syntheses and Crystallization of mineralogically relevant chalcogenide glasses

Abstract

Mineralogically relevant chalcogenide glasses with the composition CuxBi5Ag5 (As0.33S0.335Se0.335)90_x (x52, 6, and 10, in mol%) that approximate the chemistry of some unusual sulphide mineral assemblages were synthesized. The differential thermal analyses revealed that the glass transition temperature (Tg), onset crystallization temperature (Tc), and peak temperature of crystallization (Tp) first increase significantly with an increasing Cu content from 2 to 6 mol%, and then remain almost constant when the Cu content further increases to 10 mol%; the glass thermal stability also increases with an increasing Cu content. Both dry annealing and hydrothermal treatments were carried out in the temperature range of 2071–3311C for up to 96 h. X-ray diffraction analyses on annealed samples showed that dry annealing and hydrothermal treatments produced different phase assemblages. Dry annealing produced crystallized phases AgBiSe2 (bohdanowiczite), Cu2Se (berzelianite), Ag3AsS3 (xanconthite), Cu3AsS4 (luzonite), AgBi3S5, and As4 CuS9, while hydrothermal treatments produced phases AgBiSe2 (bohdanowiczite), AgBi3S5, and AgAsSe2. This case study presents a new way for studying the formation and alteration of minerals in nature.