31P nuclear magnetic resonance and X-ray diffraction study of Na-Sr-phosphate glass-ceramics

A set of Na-Sr-phosphate glass and glass-ceramic samples, with general formula xSrO:(0.55-x)Na2O:0.45P2O5, were prepared and analysed by solid state 31P nuclear magnetic resonance spectroscopy and X-ray powder diffraction. The results show the presence of Q1 and Q2 phosphate species in all samples. At low concentrations of Sr2+ (x £ 0.20) the strontium is preferentially incorporated in Sr2+-Q1 crystalline phases, and only at higher Sr2+ concentrations are crystalline phases present which Sr2+ is associated with Q2 phosphate units.