Thermodynamics Research Center / ThermoML | Thermochimica Acta

Effect of small size of particles on thermal expansion and heat capacity of Ag2S silver sulfide

Gusev, A.I., Sadovnikov, S.I.
Thermochim. Acta 2018, 660, 1-10
ABSTRACT
The thermal expansion and heat capacity of coarse-crystalline (bulk) and nanocrystalline silver sulfide Ag2S have been studied by dilatometry and differential scanning calorimetry methods in the temperature interval from 290 to 970 K. The thermal expansion coefficient and heat capacity of nanocrystalline silver sulfide in the examined temperature range are larger than the same properties of coarse-crystalline sulfide. It is shown that these differences are due to a small particle size which leads to the restriction of the phonon spectrum on the side of low and high frequencies. It is established that the acanthite a-Ag2S to argentite a-Ag2S and argentite a-Ag2S to a- Ag2S phase transformations are the first-order phase transitions, and the temperatures and enthalpies of these transformations have been determined.
Compounds
# Formula Name
1 Ag2S silver sulfide
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
  • 1
  • Triple point temperature, K ; Crystal 3
  • Crystal 3
  • Crystal 2
  • Air at 1 atmosphere
  • DSC
  • 1
  • POMD
  • 1
  • Triple point temperature, K ; Crystal 2
  • Crystal 2
  • Crystal 1
  • Air at 1 atmosphere
  • DSC
  • 1
  • POMD
  • 1
  • Molar enthalpy of transition or fusion, kJ/mol ; Crystal 3
  • Crystal 3
  • Crystal 2
  • Air at 1 atmosphere
  • DSC
  • 1
  • POMD
  • 1
  • Molar enthalpy of transition or fusion, kJ/mol ; Crystal 2
  • Crystal 2
  • Crystal 1
  • Air at 1 atmosphere
  • DSC
  • 1
  • POMD
  • 1
  • Triple point temperature, K ; Crystal 3
  • Crystal 3
  • Crystal 2
  • Air at 1 atmosphere
  • Volume change
  • 1
  • POMD
  • 1
  • Triple point temperature, K ; Crystal 2
  • Crystal 2
  • Crystal 1
  • Air at 1 atmosphere
  • Volume change
  • 1
  • POMD
  • 1
  • Molar heat capacity at constant pressure, J/K/mol ; Crystal 3
  • Temperature, K; Crystal 3
  • Pressure, kPa; Crystal 3
  • Crystal 3
  • DSC
  • 150
  • POMD
  • 1
  • Molar heat capacity at constant pressure, J/K/mol ; Crystal 2
  • Temperature, K; Crystal 2
  • Pressure, kPa; Crystal 2
  • Crystal 2
  • DSC
  • 389
  • POMD
  • 1
  • Molar heat capacity at constant pressure, J/K/mol ; Crystal 1
  • Temperature, K; Crystal 1
  • Pressure, kPa; Crystal 1
  • Crystal 1
  • DSC
  • 73