Additive Energy Relationships in Oxygen-Containing Crystals and Glasses
JSGT 1946 V30 T318-T326
Values have been computed for the energies of formation from their component ions in the gaseous state, of a large number of oxygen-containing inorganic crystals and glasses. These energies of formation can be computed approximately by the addition of energy constants characteristic of the component positive "ions" (elements other than oxygen). These energy constants depend primarily on the ionic charge, but also on the inter-atomic distance between positive and negative ions, on the co-ordination numbers, and other factors.
Minor deviations from constancy of the energy constants for phosphorus and silicon can be related to variations in the phosphorus–oxygen or silicon–oxygen ratio and so to the proportion of oxygen atoms in the PO4 or SiO4 groups which are shared with other phosphorus or silicon atoms. SiO4 or PO4 groups differing by more than one in the number of shared oxygen atoms tend to react together and so probably exist together only rarely, if at all, in the same substance.
Maurice L. Huggins & Kuan-Han Sun