Abstract
The standard thermodynamic properties (Δf G°, S°, Δf H°) of the following synthetic minerals and compounds in the Ag-Au-Se and Ag-Au-Te systems were determined by the EMF method: β-Ag2Se (low-temperature naumannite), α-Ag2Se (high-temperature naumannite), Ag3AuSe2 (fischesserite), AuSe, Ag5Te3 (stützite), Ag2 Te (hessite), and Ag3AuTe2 (petzite). All minerals and compounds were produced by solid-phase synthesis from elements or electrum of the given composition in evacuated ampoules made of quartz glass. The phases were verified by X-ray diffraction analysis, microscopically in reflected light, and with an electron microprobe. The absence of the ternary compound AgAuSe in the Ag-Au-Se system was confirmed by solid-phase annealing. On the basis of experimental data on the electromotive force E versus temperature, the equations E(T) were calculated, from which the temperature-dependent relationships of the Gibbs energy in the relevant reactions and the standard thermodynamic functions of compounds within the range 300–502 K were obtained.
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Original Russian Text © E.A. Echmaeva, E.G. Osadchii, 2009, published in Geologiya Rudnykh Mestorozhdenii, 2009, Vol. 51, No. 3, pp. 276–288.
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Echmaeva, E.A., Osadchii, E.G. Determination of the thermodynamic properties of compounds in the Ag-Au-Se and Ag-Au-Te systems by the EMF method. Geol. Ore Deposits 51, 247–258 (2009). https://doi.org/10.1134/S1075701509030076
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DOI: https://doi.org/10.1134/S1075701509030076