Observation of a Continuous Random Network Structure in Ge_xSe_(100-x) Glasses: Results from High-Resolution ~(77)Se MATPASS/ CPMG NMR Spectroscopy

摘要

The coordination environments of Se atoms in binary Ge_xSe_(100-x) glasses with 5 < x ≤ 30 are investigated using a novel, two-dimensional ~(77)Se nuclear magnetic resonance (NMR) spectroscopic technique. The high-resolution isotropic ~(77)Se NMR spectra allow for the identification of up to four distinct Se sites in these glasses. The chemical shift tensor parameters for these sites offer unique insights into their local site symmetries and nearest- and next-nearest-neighbor coordination environments. The structural results, when taken together, provide direct evidence in favor of the existence of a randomly connected network of GeSe4 tetrahedra and Se—Se chain fragments in these glasses.