Local structure of six-coordinated silicon in Li2O-SiO2-P2O5 glasses by transmission XAFS experiments

Abstract

Six-coordinated silicon [6]Si was observed by Si and P K-edge XAFS measurements in xLi2O-ySiO2-(100-y)P2O5 glasses (x = 25 and 33, y = 40, 45, 50, 55, and 60). Si K-edge EXAFS spectra of the glasses indicated the co-existence of [6]Si and four-coordinated silicon [4]Si. The proportion of octahedral [SiO66-] to [6]Si depends upon the alkali content and the [SiO66-]/[SiO44-] tetrahedral ratios were estimated by Si K-edge XANES spectra. The interatomic distances were 1.88–1.90 Å for Si-O and 1.55–1.61 Å for P-O and the amounts of [SiO66-] were 11.8–46.9%.