posted on 2014-09-11, 00:00authored byThoralf Krahl, Gudrun Scholz, Erhard Kemnitz
Nanoscaled
Ca1–xYxF2+x (x = 0...0.40)
was prepared on the new fluorolytic sol–gel route using organic
precursors and anhydrous HF. These nonstoichiometric fluorite-type
phases were investigated using 19F MAS and 19F–89Y CP MAS NMR. Excess fluoride ions occur as
point defects for x ≤ 0.01. For x > 0.01 excess fluoride ions start clustering. The 19F spectra of these phases can be fully explained by assuming a distribution
of Ca2+ and Y3+ around fluoride ions. Y3+ is distributed within the crystal lattice of CaF2, with higher concentrations near fluoride clusters. Two different
coordination polyhedra for Y3+ are observed. The correlation
between 19F and 89Y signals was established.