Coloration and Chemical Bonding State of Sulfur in R2S-B2O3 (R=Li, Na, K) Glasses.

Abstract

Simple binary alkali borate glasses containing sulfur were prepared by conventional melt quench method and chemical bonding states of sulfur were investigated by means of ultraviolet-visible (UV-VIS) spectroscopy, X-ray photoelectron spectroscopy (XPS) and 11B MAS-NMR measurement. The glass samples were colored and colors changed with glass composition and alkali species. The blue coloration by absorption at around 585nm was explained with the formation of S3- anion spices. On the other hand, the glass samples colored in brown or red showed absorption spectrum around 450nm because of the formation of Sx2- anion (polysulfide ion) speices. S2p binding energy was around 161eV, and this values was lower than that of orthorhombic crystalline sulfur. From these results, it was suggested that sulfur was present with a negative charge in R2S-B2O3 glasses. In colored reddish brown regions, the formation of non-bridging oxygen from O1s spectrum in the glasses was noticed. Therefore, it is suggested that the formation of nonbridging oxygen in glasses largely effect the variation of sample coloration. The estimated fraction of fourcoordinated boron from 11B MAS-NMR measurment was nearly equal to oxide glass systems. As a result, it is assumed that the effect of sulfur on the conversion of boron coordinate number is small because of a low solubility of sulfur in this glass system.