State of water in amorphous calcium and calcium-magnesium phosphates

Fourier-transform infrared spectra of three samples of deposited amorphous phosphates, calcium monodiphosphate (orthopyrophosphate) with a molar ratio 2P/(2P + 1P) of ∼0.3, calcium magnesium monophosphate with an atomic ratio Mg/(Mg + Ca) of ∼0.3, and calcium-magnesium monodiphosphate with a molar ratio 2P/(2P + 1P) of ∼0.1 and atomic ratio Mg/(Mg + Ca) of ∼0.1, were analyzed. On the basis of the observed similarity between the v(OH), δ(OH) and (δ + ω)(OH) lines in the spectra of these phosphates and liquid water analogous states of water molecules therein were assumed. It was presumed that the formation of amorphous phosphates involves deposition of poorly soluble substances on the surface of water nanoclusters.