Thermal Analyses of Silver-Based Sulfosalts in Air

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Publication Details

List of Authors: Fiseha Tesfaye, Daniel Lindberg
Editors: Antoine Allanore, Guillaume Lambotte, Jonghyun Lee
Publication year: 2017
Publisher: Springer
Book title: Materials Processing Fundamentals 2017
Title of series: The Minerals, Metals & Materials Series
Start page: 55
End page: 64
ISBN: 978-3-319-51579-3
eISBN: 978-3-319-51580-9
ISSN: 2367-1181


Abstract

The sulfosalts Ag 0.93Cu 1.07S (stromeyerite) and α-AgBiS 2 (schapbachite) have been studied under oxidizing conditions at elevated temperatures. The sulfosalts were synthesized from the pure simple sulfides in evacuated quartz ampoules. The synthesized samples were thermally analyzed in the temperature range from 298 to 1173 K by a simultaneous DTA-TGA analyzer . Based on the DTA measurements the phase transition of stromeyerite to the solid solution (Cu, Ag) 2S(hcp) in air is determined to be T = (360.9 ± 2) K. For the first time, maximum thermal stability of (Ag, Cu) 2S in an oxidizing atmosphere close to the partial pressure of oxygen in air ( P(O 2) ≈ 0.20 atm) is determined to be below T = (614 ± 2) K, above which it oxidizes to form Ag, CuO and Ag 2SO 4. The melting temperature of Ag 2SO 4 determined from the cooling DTA curve, T = (932.76 ± 2) K, is in good agreement with the literature value. Below T = 1173 K, the oxidation process for schapbachite in air has been indirectly determined to be: 2AgBiS 2 + 5.5O 2(g) ⇄ 2Ag + Bi 2O 3 + 4SO 2(g).


Keywords

Optimization, Oxidation/Reduction, Silver, sulfosalts, sulphides, Sustainability

Last updated on 2019-20-10 at 01:33