Emerging role of local and extended range molecular structures on functionalities of topological phases of (Na2O)(x)(P2O5)(100-)(x)glasses using Raman scattering and modulated DSC

摘要

Raman scattering is a powerful probe oflocal structure (LS)of glasses. In Sodium Phosphate Glasses (SPGs), we show that bothLScomposed of Q(n)species andExtended Range Structures (ERS)composed of Long Chains (LCs), Large Rings (LRs), and Small Rings (SRs) can be decoded by Raman scattering. The trimodal distribution of P-O(terminal)stretch modes of Q(2)species and P-O(bridging)atx ERS. These two pairs of triads of modes are uniquely identified with Q(2)units present in either LCs, or LRs, or SRs. The existence three phases of c-NaPO(3)composed of 3-membered rings, 6-membered rings, and infinitely long chains has facilitated the identification. The Intermediate Phase (IP) in SPGs extends in the 37.5 x < 46.0% range, the Stressed-rigid Phase in the 46.0% x < 50%, and the Flexible Phase in the 18% x < 37.5% range of soda. We show the IP consists predominantly of LCs (82%), with a minority of LRs (15%) and SRs (3%). The LR- and SR-fractions increase measurably in the non-IP phases. The structural finding is in harmony with the high configurational entropy of the IP glasses that leads aging to be qualitatively suppressed.