Vibrational spectra and structure of AsPS glasses

Abstract

A structural model for AsPS glasses is proposed from an analysis of Raman and infrared spectra of two series of glasses with compositions (As 2S 3) 1 − x (P 2S 5) x with x = 0 – 0.7 and As x P x S 1−2 x with x = 0.10-0.16. The structural network in these glasses is composed of AsS 3 2 and S=PS 3 2 structural units forming 8-membered rings of As 2P 2S 4. The Raman spectra of these glasses are characterized by a sharp strong Raman band of 418 cm −1 ascribed to the breathing vibration of the rings. In the S-rich compositional region lying under the As 2S 3P 2S 5 line, towards the S corner of the AsPS phase diagram, sulfur atoms form S 8 molecules inside the structural network. In the 31P MAS-NMR spectrum by a single line with the chemical shift δ( 31 P) = 113.4 ppm is due to the S= PS 3 2 coordination of the phosphorus atom.