Structural investigations of yNa2S + (1 − y)PS5/2 glasses using Raman and infrared spectroscopies

► Two transparent glassy regions, 0.33 ≤ y ≤ 0.55 and 0.65 ≤ y < 0.67 ► Edge-sharing tetrahedra in the NaPS3 composition, y = 0.33, form discrete P2S62 − anions. ► Na4P2S7, y = 0.5, loses a bridging sulfur to create Na4P2S6 groups. ► Homoatomic PP and/or SS bonds in all compositions ► P4Sx molecular cages may exist in all compositions.