Application of the constant stoichiometry grouping concept to the Raman spectra of Pb(PO3)2-TeO2 glasses

Pb(PO3)2-TeO2 glasses in the whole range of glass composition were first obtained and their properties (refractive index, density, Tg and light scattering losses) were determined. Based on the vibrational spectroscopy data a new approach was applied to investigate the interactions of initial oxides in melts resulted in so-called constant stoichiometry groupings (CSGs) formation symbolizing intermediate range order in glasses. Vibrational spectra of glasses are interpreted as a superposition of unchangeable spectral forms (principal spectral components (PSCs)) belonging to CSGs: PbO · P2O5, TeO2 · 2PbO · 2P2O5, TeO2 · PbO · P2O5, TeO2, and possibly 2TeO2 · PbO · P2O5 and 6TeO2 · PbO · P2O5. In this work Multivariate Data Analysis has been applied as the independent mathematical tool to decompose Raman spectra of glasses and reveal the number of PSCs. It is shown that application of factor analysis results in the same five PSCs that confirms our data obtained from the CSG concept. This concept allows also the prediction of the existence of unknown compounds, and correspondingly some crystals (TeO2⋅ 2PbO⋅2P2O5 and others) were revealed by XRPD of the crystallized glasses. The CSG concept opens the way for elaboration of low scattering glasses as candidates for Raman amplifiers. It is shown that Pb(PO3)2-TeO2 glasses with small content of TeO2 are of interest to photonic technology.