Silver environment and covalent network rearrangement in GeS₃–Ag glasses

Abstract

The structure of Ag-doped GeS3 glasses (0,15,20,25 at.% Ag) was investigated by diffraction techniques and extended X-ray absorption fine structure measurements. Structural models were obtained by fitting the experimental datasets simultaneously by the reverse Monte Carlo simulation technique. It is observed that Ge has mostly S neighbours in GeS3, but Ge-Ge bonds appear already at 15% Ag content. Sulphur has ~2 S/Ge neighbours over the whole concentration range, while the S-Ag coordination number increases with increasing Ag content. Ag-Ag pairs can already be found at 15%Ag. The Ag-S mean coordination number changes from 2.17±0.2 to 2.86±0.2 between 15% and 25% Ag content. Unlike As-S network in AsS2-25Ag glass, the Ge-S network is not fragmented upon Agdoping of GeS3 glass.

Structure of amorphous Ag/Ge/S alloys: experimentally constrained density functional study

“…There are interesting differences between the results for Ag-GeS 3 [21] and those found here for compounds with a higher Ge:S ratio. The higher S content in the former means that S-S bonds are significant for all Ag concentrations investigated.…”

“…The coordination numbers characterizing the host covalent network (e.g. Ge-Ge, Ge-S, S-S) do not depend on the composition between 15-25% Ag content (table 3 of [21]), suggesting that Ag occupies the free volume of the covalent network without breaking it, as found in the present work. However, a strong network rearrangement for Ag content below 15% is manifest in the formation of Ge-Ge bonds.…”

“…XRD and ND studies of Ge x S 1−x alloys with 0.333 ≤ x ≤ 0.467, sometimes termed as "Ge-rich" because they have a larger Ge/S ratio than in GeS 2 , showed different structural patterns from those found in GeS 2 [20]. Rátkai et al [21] have performed a reverse Monte Carlo analysis of XRD, ND, and EXAFS data on GeS 3 doped with up to 25 at. % Ag.…”

“…XRD and ND studies of Ge x S 1−x alloys with ⩽ ⩽ x 0.333 0.467, sometimes termed as 'Ge-rich' because they have a larger Ge/S ratio than in GeS 2 , showed different structural patterns from those found in GeS 2 [20]. Rátkai et al [21] have performed a reverse Monte Carlo analysis of XRD, ND, and EXAFS data on GeS 3 doped with up to 25 at.% Ag. Ge has mainly S neighbours in GeS 3 , but Ge-Ge and Ag-Ag bonds appear already in (GeS 3 ) 0.85 -Ag 0.15 , and the S-Ag coordination number increases with increasing Ag content.…”

Short‐ and intermediate‐range order in amorphous GeTe

“…The strong signal in the low‐ Q region of the Ge–Te correlation indicates a strong Ge–Te background network. Such a network is typical for glasses with a large portion of Ge–chalcogenide bonds, e.g., Ge–Se or Ge–S glasses or the Ge–Cu–Te system (). This network is formed mainly by connected GeX 4 building blocks (X = chalcogenide).…”