Preparation and NMR Analysis of BAP System Glasses Doped with Rare Earths

The glass-forming region of BaO-Al2O3-P2O5(BAP) glass doped with high Sm2O5 content was studied by two-step melt method. With increasing Sm2O3 of content, the forming range of BAPS glasses would shrink and tend to close ellipse, above 20% of Sm2O3 content in either case resulted in the partial devitrification of glass. The 31P and 27Al MAS NMR spectra were measured and analyzed for BAP glasses that contain distinct compositions, different heat history and Sm2O3 content. The NMR spectra results showed that Q2 type [PO4] tetrahedron was the dominant P sites, and the aluminum ions present in BAP glasses were [AlO4] and [AlO6]. The influence was not significant from glasses composition, heat history and the Sm2O3 content on the phosphorus structural units, contrarily, increase of the P/Al ratio led to the conversion of [AlO6] to [AlO4] units. As well as heat treatment and increase of Sm2O3 content resulted in the conversion of [AlO6] to [AlO4] units.