²⁷Al MAS NMR study on anion coordination around Al³⁺ in AlF₃-BaF₂-BaCl₂-CaF₂-YF ₃-EuF₃ glasses

²⁷Al MAS NMR spectra of 12 fluoroaluminate crystals with known crystal structures and 40AlF₃·(20-x)BaF₂·xBaCl ₂·20CaF₂·17YF₃·3EuF ₃·glasses (x=0,3,6,9 and 12) in mol% were measured to examine the anion coordination environments around Al³⁺ in the glasses. All the glasses gave NMR spectra with very similar line profiles, indicating that the anion coordination environments around Al³⁺ are almost the same, and that only F^- bonds to Al³⁺ regardless of the substitution of Cl for F. A comparison of the isotropic chemical shift values and the line profiles between glasses and fluoroaluminate crystals concludes that only AlF₆ octahedra are present in the glasses and that these AlF₆ octahedra mainly build up chains and/or rings by sharing the two corners in cis-configuration. Moreover, fairly sharp and symmetric line-profiles in the glasses suggest considerably high symmetry in the F^--coordination around Al³⁺.