On the structure of phosphosilicate glasses

Abstract

Abstract Vibrational spectra of phosphosilicate glasses with P 2 O 5 concentrations up to 15 mol% are investigated by the methods of Raman spectroscopy and quantum-chemical modeling. We have found that the Raman band at 1320 cm À1 characteristic for such glasses is not simple and may be decomposed into two components with frequencies at %1317 and %1330 cm À1 caused in our opinion by single phosphorus centers (O@PO 3 tetrahedra surrounded by SiO 4 ones) and by double phosphorus centers (pairs of O@PO 3 tetrahedra bonded by a common oxygen atom). In the investigated phosphosilicate glasses manufactured by MCVD and SPCVD methods the ratio of concentrations of single and double centers varies from 1:5 to 1:2. A novel interpretation of the Raman bands distinct from the traditional one is suggested. The approach to the Raman spectra analysis developed in this article can be applied for control and optimization of manufacturing process of phosphosilicate and similar glasses as well as optical fibers