Synthesis and crystal structure of three new rare earth oxyfluorides related to baddeleyite [LnOF; Ln = Tm,Yb,Lu]

Article abstract of DOI:10.1016/0025-5408(94)90183-X

The three LnOF compounds (Ln = Tm, Yb, Lu) have been prepared and shown to be isostructural with the α-ZrO₂, baddeleyite. The crystal structure has been refined by a Rietveld analysis of the X-ray powder pattern of the YbOF compound (space groupe P2₁/c, a = 5.5052(4) angstroms, b = 5.4245(4) angstroms, c = 5.5219(4) angstroms, β = 99°68, Z = 4). The strict anionic order observed (alternate 4⁴ layers of oxide anions and 3².4.3.4 layers of fluoride anions) has been analyzed with respect to the parent fluorite structure and to other to isostructural compounds like α-ZrO₂, TaON.