Short range order characterization of the Na2SÂ +Â SiS2 glass system using Raman, infrared and 29Si magic angle spinning nuclear magnetic resonance spectroscopies

Sodium thiosilicate glasses are of interest in electrochemical applications as fast ion conducting solid state electrolyte materials. While some structural studies have been performed on this glass series, their short range order (SRO) structure has not been fully realized. Specifically the SiS4 tetrahedra corner sharing behavior in these glasses appears to be less understood, particularly the existence and nature of the Si3, where the superscript describes the number of bridge bonds of the form SiSSi, structure in this glass system has not been fully examined. In this paper, glasses and polycrystals in the sodium thiosilicate system have been explored and characterized using a combination 29Si magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy, infrared (IR) spectroscopy and for the first time Raman spectroscopy. Raman and IR spectroscopy have been used to determine the composition dependence of the structural units in this system. Specifically, the Raman spectra were used to differentiate corner shared Si3, Si2, and Si1 units and edge shared Si2 structure units.29Si MAS NMR spectra were then deconvoluted to determine the composition dependence of the populations of these different structural units.