Nanostructured crystals of the fluorite phases Sr{sub 1-x}R{sub x}F{sub 2+x}(R-rare-earth elements) and their ordering: II. Crystal structure of the ordered Sr{sub 4}Lu{sub 3}F{sub 17} phase
Journal Article
·
· Crystallography Reports
- Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)
The crystal structure of the ordered phase Sr{sub 4}Lu{sub 3}F{sub 17} prepared by directed crystallization of the melt has been investigated. The crystals have a trigonally distorted fluorite lattice (space group R3-bar, Z = 6, a = 10.615(2) A, c = 19.547(6) A). The Sr{sub 4}Lu{sub 3}F{sub 17} phase is isostructural to Ba{sub 4}R{sub 3}F{sub 17} (R = Y, Yb). The distortions of the fluorite cation sublattice manifest themselves in the splitting of the only mixed position (Sr, Lu) into three positions: Sr(1), Sr(2), and Lu. All Lu{sup 3+} atoms are displaced from the center of the [Sr{sub 8}{l_brace}Lu{sub 6}F{sub 36+1}{r_brace}F{sub 32}] octacubic cluster in the [001]{sub cub} direction, and the Sr(1) cations are displaced toward the center of the octacubic cluster in the [111]{sub cub} direction. The coordination numbers of the Lu, Sr(1), and Sr(2) cations are 8, 10, and 11, respectively. The distortions of the fluorite anion sublattice are caused by the incorporation of additional anions into both the center of the octacubic cluster and the {l_brace}F{sub 8}{r_brace} cubic holes outside the cluster.
- OSTI ID:
- 22050825
- Journal Information:
- Crystallography Reports, Journal Name: Crystallography Reports Journal Issue: 3 Vol. 54; ISSN CYSTE3; ISSN 1063-7745
- Country of Publication:
- United States
- Language:
- English
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