Phase relations, ionic transport and diffusion in the alloys of Cu2S-Ag2S mixed conductors

Abstract

Abstract.Results are reported of the phase relations in the (Agx.~2Cu~.x)2 S system, ionic conductivity, self-diffusion and chemical diffusion coefficients for the solid solutions as a function of the composition x, degree of non-stoichiometry 8, and temperature in the range 473 -673 K. The extensions of the homogeneity regions for single-phases are determined. Total and partial ionic conductivity values are given for copper and silver ions for the solid solutions. Measurements ot" the self-diffusion coefficient and the correlation factors are reported. It is shown that for solid solutions that the chemical diffusion is well described in terms of the phenomenological theory of ionic transport in mixed ionic electronic conductors.

Phase transitions in jalpaite, Ag3CuS2

“…Note that diffraction results on a number of copper and silver based chalcogenides and halides (for instance, results of [17][18][19][20][21]) imply that the ionic conductivity can be sensitive to details of the cation redistribution between available interstitial sites versus temperature as well as to the stoichiometry of the material. Taking this into account, we suggest a correlation between the results of the electrochemical measurements from Kadrgulov et al [3], which revealed only a relatively modest increase in the ionic conductivity with temperature within fcc-(Ag x Cu 1-x ) 2 S, and our diffraction results, which show no pronounced cation redistribution. The same correlation was supposed for related superionic fcc-AgCuSe [19], fcc-AgCuS [21] and fcc-(AgI) x -(PbI 2 ) 1-x with x= 5 4 and 3 2 [17].…”

“…Neutron and synchrotron diffraction data collected at 473 K were used. The refinements were based on Im 3 m symmetry with the S 2− located in the 2(a) sites at (0, 0, 0 3 . All these models were unstable in the refinement due to high correlations between the fitted parameters and produced very poor fits to the experimental data.…”

“…This is a clear indication of disorder but does not give any information about the actual cation positions. Furthermore, the following models with cations distributed between two sites were tested: between 8(c) sites at ( 4 1 <x< 3 1 and 32(f) in (x, x, x) with 3 1 <x< 2 1 (this model implies cation distribution between displaced tetrahedral and displaced octahedral sites), the results of these refinements are not presented in table 3. Models 6 and 7 slightly improve the goodness-of-fit in comparison to model 5.…”

“…cm −1 and demonstrate negligible dependence on temperature [3]. Furthermore, an implementation of jalpaite as ion-selective electrode membrane for the environmental monitoring of copper ion activity in the marine waters is of considerable interest [4,5].…”

Synthesis and ammonia sensing property of Ag3CuS2 nanocages obtained from Cu7S4 18-facet hollow nanopolyhedra

“…Furthermore, ionic conductivities of (Ag x Cu 1Àx ) 2 S compounds, with x=0; 0.2; 0.4; 0.6 and 1, had been studied by Kadrgulov et al. The superionic face-centered cubic phases of these compounds showed negligible dependence on temperature [9]. Recently, Trots et al investigated the phase transition behaviors of silver copper sulfide in a wide range of temperature [10][11][12].…”