Thermal Analyses of Silver-Based Sulfosalts in Air

Fiseha Tesfaye; Daniel Lindberg

doi:10.1007/978-3-319-51580-9_6

Thermal Analyses of Silver-Based Sulfosalts in Air

Fiseha Tesfaye, Daniel Lindberg

Technologies for a Sustainable Future

Research output: Chapter in Book/Conference proceeding › Chapter › Scientific › peer-review

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).

Original language	Undefined/Unknown
Title of host publication	Materials Processing Fundamentals 2017
Editors	Antoine Allanore, Guillaume Lambotte, Jonghyun Lee
Publisher	Springer
Pages	55–64
ISBN (Electronic)	978-3-319-51580-9
ISBN (Print)	978-3-319-51579-3
DOIs	https://doi.org/10.1007/978-3-319-51580-9_6
Publication status	Published - 2017
MoE publication type	A3 Part of a book or another research book

Keywords

Optimization
Oxidation/Reduction
Silver
Sustainability
sulfosalts
sulphides

Access to Document

10.1007/978-3-319-51580-9_6

https://www.springerprofessional.de/en/thermal-analyses-of-silver-based-sulfosalts-in-air/12047420

Cite this

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title = "Thermal Analyses of Silver-Based Sulfosalts in Air",

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).",

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N2 - 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).

AB - 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).

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