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 P4Se3-As4Se3 join with 0 to 70 mol% P4Se3 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 PxAs4-xSe3 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.