Structure of molecule-rich chalcogenide glasses along the join P4Se3-As4Se3: Results from 77Se and 31P NMR and Raman spectroscopy

The atomic structure of unusually molecule-rich glasses along the P ₄Se ₃-As ₄Se ₃ join with 0 to 70 mol% P ₄Se ₃ is studied using Raman, ⁷⁷Se magic-angle-spinning (MAS) and 2D ³¹P phase adjusted spinning sideband (PASS) nuclear magnetic resonance (NMR) spectroscopy. When taken together, the spectroscopic results indicate the coexistence of cage-like P _xAs _4-xSe ₃ molecular moieties and corner-shared P- and As- containing pyramidal network moieties in the structure of these glasses. Increasing substitution of As with P gives rise to a monotonic increase in the total molecule:network ratio, which is shown to be consistent with the compositional variation in the glass transition temperature.