Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

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

Tesfaye, F.[Fiseha], Taskinen, P.[Pekka]
J. Chem. Thermodyn. 2014, 70, 219-226
ABSTRACT
Thermodynamic properties of schapbachite (a-AgBiS2) in the phase assemblage a-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 b-AgBi1+xS2 to a-AgBi1+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 (a-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 (a-AgBi1+xS2) have been evaluated. It has been observed that within the temperature range from (474 to 680) K, schapbachite saturated with bismuth (a-AgBi1+xS2) is thermodynamically more stable than the stoichiometric schapbachite (a-AgBiS2).
Compounds
# Formula Name
1 Ag silver
2 Bi bismuth
3 S sulfur
4 AgBi3S5 bismuth silver sulfide (Bi3AgS5)
5 AgBiS2 bismuth silver sulfide (BiAgS2)
Datasets
The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type Compound-# Property Variable Constraint Phase Method #Points
  • POMD
  • 5
  • Triple point temperature, K ; Crystal 2
  • Crystal 2
  • Crystal 1
  • Air at 1 atmosphere
  • from the slopes of electrochemical cell potential
  • 1
  • POMD
  • 5
  • Molar enthalpy of transition or fusion, kJ/mol ; Crystal 2
  • Crystal 2
  • Crystal 1
  • Air at 1 atmosphere
  • Electrochemical cell potential
  • 1
  • POMD
  • 2
  • Triple point temperature, K ; Crystal
  • Crystal
  • Liquid
  • Air at 1 atmosphere
  • from the slope of electrochemical cell potential
  • 1
  • POMD
  • 2
  • Molar enthalpy of transition or fusion, kJ/mol ; Crystal
  • Crystal
  • Liquid
  • Air at 1 atmosphere
  • Electrochemical cell potential
  • 1
  • RXND
  • 1
  • 2
  • 5
  • 4
  • Molar Gibbs energy of reaction, kJ/mol
  • Calculated from EMF cell potential
  • 8
  • RXND
  • 1
  • 2
  • 5
  • 4
  • Molar Gibbs energy of reaction, kJ/mol
  • Calculated from EMF cell potential
  • 9
  • RXND
  • 1
  • 2
  • 5
  • 4
  • Molar Gibbs energy of reaction, kJ/mol
  • Calculated from EMF cell potential
  • 16
  • RXND
  • 1
  • 2
  • 3
  • 5
  • Molar enthalpy of reaction, kJ/mol
  • Electrochemical cell potential
  • 1