Sulfur–selenium isomorphous substitution and morphotropic transition in the Ag3Au(Se,S)2 series

Abstract

Gold–silver sulfoselenides of the series Ag3AuSexS2–x (x = 0.25; 0.5; 0.75; 1; 1.5) were synthesized from melts on heating stoichiometric mixtures of elementary substances in evacuated quartz ampoules. According to X-ray single-crystal analysis, compound Ag3Au1Se0.5S1.5 has the structure of gold–silver sulfide Ag3AuS2 (uytenbogaardtite) with space group R3¯c. The volume of this compound is 1.5% larger than that of the sulfide analog. According to powder X-ray diffraction, compounds Ag3AuSe0.25S1.75 and Ag3AuSe0.75S1.25 also show trigonal symmetry. Compounds Ag3AuSeS and Ag3AuSe1.5S0.5 are structurally similar to the low-temperature modification of gold–silver selenide Ag3AuSe2 (fischesserite) with space group I4132. These data suggest the existence of two solid solutions: petzite-type cubic Ag3AuSe2–Ag3AuSeS (space group I4132) and trigonal Ag3AuSe0.75S1.25–Ag3AuS2 (space group R3¯c). It was found that fischesserite from the Rodnikovoe deposit (southern Kamchatka) contains 3.5–4 wt.% S. At the Kupol deposit (Chukchi Peninsula), fischesserite contains up to 2.5 wt.% S and uytenbogaardtite contains up to 5.3 wt.% Se. At the Ol’cha and Svetloe (Okhotskoe) deposits (Magadan Region), uytenbogaardtite contains up to 0.5 and 1.8 wt.% Se, respectively. Literature data on the compositions of silver–gold selenides and sulfides from different deposits were summarized and analyzed. Analysis of available data on the S and Se contents of natural fischesserite and uytenbogaardtite confirms the miscibility gap near composition Ag3AuSeS.

Synthesis and crystal structure of silver–gold sulfide AgAuS. Four-fold interpenetrated three-dimensional [(Au,Ag)10S8]-networks

“…8 This method was used for preparing Ag 2−x Au x S 9 and Ag 3 AuS 2−x Se x . 10,11 The starting materials for the synthesis were elemental silver, gold (99.99%) and sulfur (99.9%); the total weight of the mixture was ~500 mg. The accuracy of weighing was ±0.05 mg ("Mettler Instrument Ag CH-8606 Greifensee-Zurich").…”

“…The X-ray powder diffraction data of the AgAuS sample were collected on a Thermo Scientific ARL X'TRA diffractometer equipped with a Peltier cooled Si(Li) solid state detector (CuKα radiation). A sintered alumina plate (SRM 1976, a = 4.75885 (11), c = 12.993(2) Å) was used as the external standard.…”

Colloidal and Deposited Products of the Interaction of Tetrachloroauric Acid with Hydrogen Selenide and Hydrogen Sulfide in Aqueous Solutions

“…Mixed silver-gold sulfides and selenides, including nanoparticulate ones, have attracted intense interest as minerals and natural sources of precious metals [1][2][3][4][5][6][7][8][9][10][11][12][13][14] and due to high ionic conductivity, tunable optical characteristics, thermoelectric and other properties promising for materials applications [15][16][17][18][19]. Gold chalcogenides, in particular gold selenide, are much less examined, despite aqueous Au chalcogenide-derived complexes play the crucial role as carriers of gold in hydrothermal fluids and brines (e.g., [20][21][22][23][24][25] and references therein), and AuSe, Au(Se,S) and Au(Te,Se,S) phases in intergrowths with native gold have been found in the high-sulfidation epithermal deposits formed from acidic fluids [14].…”

Au‐Ag‐S‐Se‐Cl‐Br Mineralization at the Corrida Deposit (Russia) and Physicochemical Conditions of Ore Formation

“…The Corrida deposit is a new example of epithermal deposits in which Au-Ag chalcogenides (acanthite, uytenbogaardtite, fischesserite, naumannite and others) are found in significant quantities [3,7,[69][70][71]. Au-Ag chalcogenides and other gold and silver minerals found in sulfide ores (argyrodite, andorite, pyrargyrite, lenaite, chlorargyrite, bromargyrite) can be of economic importance in the future [72].…”