Lu{sub 3}O{sub 2}F{sub 5}: A new highly densified member (n=3) of the M{sub n}X{sub 2n+1} series of fluorite-related vernier phases

Journal Article · Sun Oct 01 04:00:00 EDT 1995 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/0022-4596(95)80018-K· OSTI ID:237560

Laval, J P; Taoudi, A; Abaouz, A ^[1]

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1. Universite de Limoges (France); and others

In addition to the nonstoichiometric LuO{sub 1-x}F{sub 1+2x} (0.11 {le} x {le} 0.22) domain of incommensurate vernier phases, a new stoichiometric phase Lu{sub 3}O{sub 2}F{sub 5} (x = 0.33) has been isolated. Its crystal structure has been solved by a Rietveld analysis of its powder X-ray pattern (R{sub B} = 0.047). Lu{sub 3}O{sub 2}F{sub 5} crystallizes with orthorhombic symmetry (space group: Pnma) and the unit cell parameters a = 5.544(1) {angstrom}, b = 16.875(3) {angstrom}, c = 5.292(1) {angstrom} and Z = 4. Its crystal structure can be described as the commensurate member n = 3 of the M{sub n}X{sub 2n}=1 series of family I vernier phases, and exhibits the highest anionic rate ever observed in such phases (MX{sub 2.33}). The crystallochemical factors justifying such a surprising anionic densification are analyzed and emphasized. A comparison with Bi{sub 3}NF{sub 6}, whose structure corresponds to the member n = 3 of the series family II vernier phases, is developed.

• OSTI ID: 237560
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 1 Vol. 119; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CRYSTAL STRUCTURE
LUTETIUM FLUORIDES
LUTETIUM OXIDES
ORTHORHOMBIC LATTICES