Glass formation and structure of melt quenched mixed oxy-sulfide Na4P2S7-xOx glasses for 0 ≤ x ≤ 5

Abstract

The structures of Na4P2S 7-xOx, 0 ≤ x ≤ 5, glasses were investigated using melt quench (MQ) samples. The short-range order (SRO) structures of these glasses were examined using a combination of Raman, Fourier Transform Infrared (FT-IR), and 31P Magic Angle Spinning NMR (31P MAS NMR) spectroscopies to determine how oxygen is incorporated into the sulfide structure. Using vibrational spectroscopy, semi-quantitative 31P MAS NMR, and charge balancing, a complete compositional map of all the SRO structures present in these glasses has been generated. From these results, full incorporation of the oxygen into the sulfide melt was found to occur across the compositional series through a structural disproportionation reaction where oxygen systematically replaces bridging sulfurs (BSs), before replacing the remaining non-bridging sulfurs (NBSs). Under the melting and quenching conditions used in this study, it was found that the melts crystallize too quickly to form homogeneous crystallite-free glasses for x > 5.