Raman spectroscopic studies of calcium-phosphate, aluminum metaphosphate-sodium fluoride and calcium metaphosphate-calcium fluoride glasses

The role of modifier on the molecular structure of Ca-phosphate, sodium fluorophosphate and sodium aluminophosphate glasses have been investigated by Raman spectroscopy. Ca-phosphate glasses for this study have the molar ratio of CaO/P₂O₅ from 1.00 to 1.50. Curve fitting procedures have been used to resolve the overlapped peaks for accurate interpretation. Amorphous species with varying chain lengths and two crystalline phases of γ- and α-Ca₂P₂O₇ have been identified. Sodium fluorophosphate glasses have been prepared from the reaction between Al(PO₃)₃ and NaF. The molar ratio of Na/P is varied from 0.900 to 2.00 and the F/P ratio is from 0.510 to 1.61. By studying the vibrational frequency shifts, species with varying phosphorus and fluorine contents and aluminophosphate compounds have been identified