Silver Sulfide Ag2S Research Articles

Superionic nanolayered structure based on amorphous Ag2Se

A regular nanocomposite, consisting of 62 alternating Ag2Se and chalcogenide glass nanolayers of identical thickness, was fabricated by Pulsed Laser Deposition. The total thickness of the nanostructure is 700 nm. The Ag2Se layers in the nanostructure are amorphous in a wide temperature range, unlike the individual layers of this compound. A method for determining values of ionic and electronic conductivity components is proposed. It was found that the obtained nanostructure possesses high ionic conductivity at room temperature (≈10 Ω−1cm−1), which is comparable to the conductivity of superionic electrolytes.Synthesized nanostructures may find applications as solid electrolytes, as well as in the production of flexible electronics in combination with silver sulfide Ag2S.

Argentite–Acanthite Transition in Silver Sulfide as a Two-Sublattice Ordering

We propose a model of phase transformation cubic argentite–monoclinic acanthite in silver sulfide Ag2S (AgS0.5) as ordering in two argentite sublattices. We have determined the channel of the disorder–order transition including four nonequivalent superstructure vectors of stars {k9} and {k4}. For monoclinic acanthite α-Ag2S, we have calculated the distribution function for silver atoms occupying b positions in argentite, as well as the distribution function for sulfur atoms. Ordering in both sublattices is complicated by static atomic displacements. The displacement of S atoms distort the body-centered cubic (bcc) nonmetallic argentite sublattice, forming a monoclinic lattice in which silver atoms are at large distances from one another and occupy their crystallographic positions with unit probability. We have determined the range of admissible values of long-range order parameters η9 and η4 for the model monoclinic ordered α-Ag2S phase.

Effect of Particle Size and Specific Surface Area on the Determination of the Density of Nanocrystalline Silver Sulfide Ag2S Powders

The effect of the particle size and specific surface area of silver sulfide powders on their density measured by the helium pycnometry method has been studied. Powders with different average particle sizes have been synthesized by hydrochemical deposition. The particle size of the silver sulfide powders has been determined by the Brunauer–Emmett–Teller method according to molecular nitrogen adsorption isotherms and, in the case of fine powders, by X-ray diffraction analysis according to diffraction reflection broadening. It has been shown that the density of the fine powders measured by helium pycnometry is underestimated compared with the true density, owing to the adsorption of helium by the highly developed surface of these powders.

Thermal expansion and the heat capacity of nanocrystalline and coarse-crystalline silver sulfide Ag2S

The thermal expansion and the heat capacity of coarse-crystalline and nanocrystalline silver sulfide Ag2S were studied by dilatometry and differential scanning calorimentry for the first time in the temperature range 290–970 K. It is found that the thermal expansion coefficient and the heat capacity of nanocrystalline silver sulfide in this temperature range are higher than those in the case of the coarse-crystalline sulfide. It is revealed that the transformation of α-Ag2S acanthite to β-Ag2S argentite and β-Ag2S argentite to γ-Ag2S phase are the first-order phase transitions; the temperatures and the enthalpies of these transformations have been determined.

Structure and stoichiometry of nanocrystalline silver sulfide

Powders of silver sulfide Ag2S with an average particle size from ~500 to ~20–40 nm have been synthesized by the chemical bath deposition. The powders with a particle size of ~500 nm have a monoclinic (space group P21/c) acanthite structure (α-Ag2S) and the stoichiometric Ag2S composition. It has been revealed for the first time that silver sulfide nanopowders have the same monoclinic acanthite α-Ag2S structure but a nonstoichiometric composition ~Ag1.93S and contain vacant sites in the metal sublattice. The change in the crystal structure upon the transition from cubic argentite β-Ag2S to monoclinic acanthite α-Ag2S is considered.

Corrosion damage to a silver coin ?Sobol??

The surface of a silver coin “Sobol’” is investigated by local x-ray fluorescence analysis and measuring the electrode potential. It is shown that the coin blackening is associated with the formation of silver sulfide Ag2S.