Experimentally determined thermodynamic properties of schapbachite (α-AgBiS2) below T = 700 K

Fiseha Tesfaye; Pekka Taskinen

doi:10.1016/j.jct.2013.11.006

Experimentally determined thermodynamic properties of schapbachite (α-AgBiS₂) below T = 700 K

Fiseha Tesfaye^*, Pekka Taskinen

^*Corresponding author for this work

Laboratory of Molecular Science and Engineering

Research output: Contribution to journal › Article › Scientific › peer-review

11 Citations (Scopus)

Abstract

Thermodynamic properties of schapbachite (α-AgBiS₂) in the phase assemblage α-AgBiS₂-AgBi₃S₅-Bi have been studied by an EMF-technique. The EMF-measurements were made on the galvanic cell Pt(-)|Ag|AgI|AgBiS₂ + AgBi₃S₅ + Bi|C|Pt(+), over the temperature range from (429 to 699) K. According to the EMF vs. temperature relations obtained, the enthalpy of the phase transformation from β-AgBi_1+xS₂ to α-AgBi _1+xS₂, at T = (465.55 ± 5) K, was calculated to be (7.3 ± 2.1) kJ · mol^-1. New experimentally determined thermodynamic properties of the bismuth-saturated schapbachite (α-AgBi_1+xS₂), for each temperature region of the stable phases Bi(s) and Bi(l), were generated and analysed in detail. Based on the experimental results, Gibbs free energies of sulfidation reactions including Ag, Bi(l), S₂(g), Ag₂S and Bi₂S₃ to produce the bismuth-saturated schapbachite (α-AgBi_1+xS₂) have been evaluated. It has been observed that within the temperature range from (474 to 680) K, schapbachite saturated with bismuth (α-AgBi_1+xS ₂) is thermodynamically more stable than the stoichiometric schapbachite (α-AgBiS₂).

Original language	English
Pages (from-to)	219-226
Number of pages	8
Journal	Journal of Chemical Thermodynamics
Volume	70
DOIs	https://doi.org/10.1016/j.jct.2013.11.006
Publication status	Published - Mar 2014
MoE publication type	A1 Journal article-refereed

Funding

The authors are grateful to Improved Sulfide Smelting (ISS) project of Fimecc Oy, ELEMET research program, and Tekes, the Finnish Funding Agency for Technology and Innovation, for financial support. This work was made as a sub task of ISS, supported financially also by Boliden Harjavalta, Boliden Kokkola Oy, Norilsk Nickel Finland Oy and Outotec (Finland) Oy.

Keywords

Electromotive force (EMF)
Saturation
Schapbachite
Solid solubility
Thermodynamic properties

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Cite this

@article{63e88325a56c4041974f55c45423708b,

title = "Experimentally determined thermodynamic properties of schapbachite (α-AgBiS2) below T = 700 K",

abstract = "Thermodynamic properties of schapbachite (α-AgBiS2) in the phase assemblage α-AgBiS2-AgBi3S5-Bi have been studied by an EMF-technique. The EMF-measurements were made on the galvanic cell Pt(-)|Ag|AgI|AgBiS2 + AgBi3S5 + Bi|C|Pt(+), over the temperature range from (429 to 699) K. According to the EMF vs. temperature relations obtained, the enthalpy of the phase transformation from β-AgBi1+xS2 to α-AgBi 1+xS2, at T = (465.55 ± 5) K, was calculated to be (7.3 ± 2.1) kJ · mol-1. New experimentally determined thermodynamic properties of the bismuth-saturated schapbachite (α-AgBi1+xS2), for each temperature region of the stable phases Bi(s) and Bi(l), were generated and analysed in detail. Based on the experimental results, Gibbs free energies of sulfidation reactions including Ag, Bi(l), S2(g), Ag2S and Bi2S3 to produce the bismuth-saturated schapbachite (α-AgBi1+xS2) have been evaluated. It has been observed that within the temperature range from (474 to 680) K, schapbachite saturated with bismuth (α-AgBi1+xS 2) is thermodynamically more stable than the stoichiometric schapbachite (α-AgBiS2).",

keywords = "Electromotive force (EMF), Saturation, Schapbachite, Solid solubility, Thermodynamic properties",

author = "Fiseha Tesfaye and Pekka Taskinen",

note = "This is my article published when I was working for the previous affiliation (Aalto University)",

year = "2014",

month = mar,

doi = "10.1016/j.jct.2013.11.006",

language = "English",

volume = "70",

pages = "219--226",

journal = "Journal of Chemical Thermodynamics",

issn = "0021-9614",

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TY - JOUR

T1 - Experimentally determined thermodynamic properties of schapbachite (α-AgBiS2) below T = 700 K

AU - Tesfaye, Fiseha

AU - Taskinen, Pekka

N1 - This is my article published when I was working for the previous affiliation (Aalto University)

PY - 2014/3

Y1 - 2014/3

N2 - Thermodynamic properties of schapbachite (α-AgBiS2) in the phase assemblage α-AgBiS2-AgBi3S5-Bi have been studied by an EMF-technique. The EMF-measurements were made on the galvanic cell Pt(-)|Ag|AgI|AgBiS2 + AgBi3S5 + Bi|C|Pt(+), over the temperature range from (429 to 699) K. According to the EMF vs. temperature relations obtained, the enthalpy of the phase transformation from β-AgBi1+xS2 to α-AgBi 1+xS2, at T = (465.55 ± 5) K, was calculated to be (7.3 ± 2.1) kJ · mol-1. New experimentally determined thermodynamic properties of the bismuth-saturated schapbachite (α-AgBi1+xS2), for each temperature region of the stable phases Bi(s) and Bi(l), were generated and analysed in detail. Based on the experimental results, Gibbs free energies of sulfidation reactions including Ag, Bi(l), S2(g), Ag2S and Bi2S3 to produce the bismuth-saturated schapbachite (α-AgBi1+xS2) have been evaluated. It has been observed that within the temperature range from (474 to 680) K, schapbachite saturated with bismuth (α-AgBi1+xS 2) is thermodynamically more stable than the stoichiometric schapbachite (α-AgBiS2).

AB - Thermodynamic properties of schapbachite (α-AgBiS2) in the phase assemblage α-AgBiS2-AgBi3S5-Bi have been studied by an EMF-technique. The EMF-measurements were made on the galvanic cell Pt(-)|Ag|AgI|AgBiS2 + AgBi3S5 + Bi|C|Pt(+), over the temperature range from (429 to 699) K. According to the EMF vs. temperature relations obtained, the enthalpy of the phase transformation from β-AgBi1+xS2 to α-AgBi 1+xS2, at T = (465.55 ± 5) K, was calculated to be (7.3 ± 2.1) kJ · mol-1. New experimentally determined thermodynamic properties of the bismuth-saturated schapbachite (α-AgBi1+xS2), for each temperature region of the stable phases Bi(s) and Bi(l), were generated and analysed in detail. Based on the experimental results, Gibbs free energies of sulfidation reactions including Ag, Bi(l), S2(g), Ag2S and Bi2S3 to produce the bismuth-saturated schapbachite (α-AgBi1+xS2) have been evaluated. It has been observed that within the temperature range from (474 to 680) K, schapbachite saturated with bismuth (α-AgBi1+xS 2) is thermodynamically more stable than the stoichiometric schapbachite (α-AgBiS2).

KW - Electromotive force (EMF)

KW - Saturation

KW - Schapbachite

KW - Solid solubility

KW - Thermodynamic properties

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