Solid-state nuclear magnetic resonance study of the structure of lanthanum phosphate crystals and glasses

Lanthanum phosphate glasses were synthesized by melt quenching and characterized by x-ray diffraction, electron microprobe analysis, and solid-state nuclear magnetic resonance spectroscopy. A range of compositions near the metaphosphate composition (75 mol% P₂O₅) was examined. Comparison of ³¹P chemical shifts and shielding anisotropies of glasses with those of the crystalline phases of La(PO₃)₃ (metaphosphate) and LaP₅O₁₄ (pentaphosphate) were consistent with the presence of primarily chainlike Q² phosphate groups.