Chemical model and some basic properties of vanadium calcium phosphate glasses

Vanadium calcium phosphate glasses of the xV 2 O 5 -(50-x)CaO–50P 2 O 5 series were studied, i.e. glasses with an expected redox reaction leading to a decrease in the oxidation state of vanadium. The course of calcinate preparation was monitored using Raman spectroscopy. Glasses are in no way mixtures of oxides, which only formally express their assumed chemical composition and only in the event that redox reactions do not occur. Therefore, the chemical composition of the glasses was determined using XRF, 31 P MAS NMR and ESR and a chemical model was designed. This is key, first of all, for calculating the molecular weight of the glasses, which is needed to determine the correct value of molar quantities. It is also the basis for interpreting properties. It was also proven using computer analysis of the ESR spectrum of vanadyl VO 2+ that its symmetry is not axial, as is commonly stated, that it is orthorhombic due to Jahn-Teller distortion.