Planar rings in glasses

Abstract

An energy minimization argument is used to predict that small order rings of bonds are likely to be planar in many glasses. The 606 and 495 cm -1 Raman “defect” lines in fused silica are then shown to be consistent with small concentrations (⩽1%) of planar 3-fold and 4-fold rings, respectively. The argument predicts this form of intermediate range order at larger concentrations in several glasses, including 3-fold planar rings in B 2O 3, while it predicts no planar rings in other glasses, including ZnCl 2.