Phosphate glasses, what is the actual chemical composition and structure of these glasses? The view of a chemist

From the point of view of the chemistry of phosphate glasses their chemical composition are discussed. Attention is paid to the issue related to the expression of chemical composition using oxides and it is shown that this way of expressing the composition is simple and in some cases suitable, but practically does not express the actual chemical composition of the glasses. The chemical composition is actually given by the chemical compounds and their individual concentrations. To obtain a realistic view of the composition, a chemical model is presented and the method of its creation is described on the basis of the experimental methods used, i.e. XRF, ESR and 31P MAS NMR. Using 31P static NMR spectra, which have not yet been used in the studies, it turns out that the structure of glass metaphosphates is more complex than corresponds to the usual idea of a chain of basic structural units.