Chemical and Structural Variety in Sodium Thioarsenate Glasses Studied by Neutron Diffraction and Supported by First-Principles Simulations
Year: 2020
Type: article
Abstract: Sodium-conducting sulfide glasses are promising materials for the next generation of solid-state batteries. Deep insight into the glass structure is required to ensure a functional design and tailoring of vitreous alloys for energy applications. Using pulsed neutron diffraction supported by first-principles molecular dynamics, we show a structural diversity of Na 2 S–As 2 S 3 sodium thioarsenate glasses, consisting of long corner-sharing (CS) pyramidal chains CS-(AsSS 2/2 ) k, small As p S q rings ( p + q ≤ 11), mixed corner- and edge-sharing oligomers, edge-sharing (ES) dimers ES-As 2 S 4, and isolated (ISO) pyramids ISO-AsS 3, entirely or partially connected by sodium species. Polysulfide S–S bridges and structural units with homopolar As–As bonds complete the glass structure, which is basically different from structural motifs predicted by the equilibrium phase diagram. In contrast to superionic silver and sodium sulfide glasses, characterized by a significant population of isolated sulfur species S iso (0.20 < S iso /S tot < 0.28), that is, sulfur connected to only mobile cations M + with a usual M/S iso stoichiometry of 2, poorly conducting Na 2 S–As 2 S 3 alloys exhibit a modest S iso fraction of 6.2%.
Source: Inorganic Chemistry
Language: English
Subfield: Ceramics and Composites
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W3093898569