Nanoscopic yttrium oxide fluorides: non-aqueous fluorolytic sol–gel synthesis and structural insights by¹⁹F and⁸⁹Y MAS NMR

Abstract

Nanoscopic yttrium acetate fluorides Y(CH(3)COO)(3-z)F(z) and yttrium oxide fluorides YO(3-z)/(2)F(z )were prepared with tunable Y/F molar ratios via the fluorolytic sol-gel route. All samples were characterized by X-ray diffraction, elemental analysis and thermal analysis. In addition, local structures of all samples were studied by (19)F MAS, (19)F-(89)Y CP MAS and (1)H-(89)Y CP MAS NMR spectroscopy and the respective chemical shifts are given. For both classes of compounds, only the fluorination using one equivalent of F (z = 1) leads to defined, well crystalline matrices: yttrium acetate fluoride Y(CH(3)COO)(2)F and r-YOF.

Local Structures of Solid Solutions Sr1–xYxF2+x (x = 0...0.5) with Fluorite Structure Prepared by Sol–Gel and Mechanochemical Syntheses

“…89 Y isotropic chemical shifts of Y 3+ coordinated by fluoride ions cover a range of approximately +25 ppm for [YF 6 ] to −130 ppm for [YF 9 ] . Eight-fold coordinated [YF 8 ] is found at −35 to −60 ppm, with square-antiprismatic coordination geometry shifted to more negative values than cubic coordination geometry. , Other solids like oxides and oxofluorides have chemical shifts far outside this range. − …”

Recent progress in solid-state NMR of spin-½ low-γ nuclei applied to inorganic materials

“…from the crystalline oxyfluoride r-YOF. 116 Yttrium was added to CaF 2 via a sol-gel route to form Ca 1Àx Y x F 2+x . 117 To enhance the yttrium NMR signal 19 F-89 Y CP was used.…”

“…115 Fluorolytic sol–gel formation of nanoscale yttrium fluorides/oxyfluorides from acetate precursors was followed by a combination of 19 F and 89 Y which included data from the crystalline oxyfluoride r-YOF. 116 Yttrium was added to CaF 2 via a sol–gel route to form Ca 1− x Y x F 2+ x . 117 To enhance the yttrium NMR signal 19 F– 89 Y CP was used.…”