H. Mueller-Bunz, Oliver Janka, T. Schleid
2007
Citations
0
Influential Citations
6
Citations
Journal
Zeitschrift für anorganische und allgemeine Chemie
Abstract
Er3O2F5: An Erbium Oxide Fluoride with Vernier-Type Structure Attempts to synthesize multinary erbium-trifluoride derivatives (e. g. Er3F[Si3O10], Er4F2[Si2O7][SiO4], CsEr2F7, and RbEr3F10) from mixtures of ErOF-contaminated erbium trifluoride (ErF3) itself and appropriate other components (such as Er2O3 and SiO2 or CsF and RbF, respectively) frequently resulted in the formation of pale pink, transparent, lath-shaped single crystals of Er3O2F5 (orthorhombic, Pnma; a = 562.48(5), b = 1710.16(14), c = 537.43(4) pm; Z = 4) as by-product, typically after seven days at 800 °C and regardless of the applied reaction-container material (evacuated torch-sealed silica or silica-jacketed arc-welded tantalum capsules). Its crystal structure, often described as a vernier-type arrangement consisting of two interpenetrating and almost misfitting lattices (ErOF and ErF3), contains two crystallographically different Er3+ cations in the eight- and seven-plus-one-fold anionic coordination of bicapped trigonal prisms. Whereas (Er1)3+ carries four O2− and F− anions each, (Er2)3+ resides in the neighbourhood of only two O2−, but five plus one F− anions. As the main structural feature, however, one can consider O2−-centred (Er3+)4 tetrahedra which share common edges to form linear double strands of the composition . Running parallel to the [100] direction and assembling like a hexagonal closest rod-packing, their electroneutralization and three-dimensional interconnection is achieved by three crystallographically independent F− anions (d(F−−Er3+) = 221 − 251 plus 281 pm) in three- and two-plus-two-fold coordination of the Er3+ cations, respectively.