Crystal structure of LiLnW{sub 2}O{sub 8} (Ln=lanthanides and Y): An X-ray powder diffraction study

Journal Article · Mon Aug 15 00:00:00 EDT 2011 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2011.05.046· OSTI ID:21580194

Postema, J M ^[1]; IJdo, D J.W. ^[1]

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1. Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, 2300 RA Leiden (Netherlands)

Crystal structures that occur in LiLnW{sub 2}O{sub 8} (Ln=lanthanides and Y) have been studied using Rietveld profile analysis of X-ray diffraction data. Two types of structures were observed. The scheelite structure of the space group I4{sub 1}/a is adopted for compounds containing large lanthanides Ln=La-Gd. For smaller lanthanides (Ln=Dy-Lu and Y) the wolframite structure with the space group P2/n is observed. In LiTbW{sub 2}O{sub 8}, both structures occur. The phase transition between the two is a slow process making the obtainment of pure low temperature phase (wolframite) difficult. The space groups P1-bar and P2, recently reported for LiEuW{sub 2}O{sub 8} and LiYW{sub 2}O{sub 8}, have not been observed in this series of compounds. - Graphical abstract: Part of the X-ray diffraction patterns of LiSmW{sub 2}O{sub 8} and LiDyW{sub 2}O{sub 8} representing two structure types in LiLnW{sub 2}O{sub 8}: the scheelite with Ln=La-Gd and wolframite with Ln=Dy-Lu and Y. In LiTbW{sub 2}O{sub 8} both the scheelite and the wolframite structures occur at high and low temperatures, respectively. Highlights: > Double tungstates of the formula LiLnW{sub 2}O{sub 8} (Ln=lanthanides and Y) were systematically synthesised and their crystal structures were determined. > LiLnW{sub 2}O{sub 8} adopt either the scheelite structure (I4{sub 1}/a) (Ln=La-Gd) or wolframite structure (P2/n) (Ln=Dy-Lu and Y). > Both structures occur in LiTbW{sub 2}O{sub 8} and the I4{sub 1}/a{yields}P2/n phase transition is a slow process. > The space groups P1-bar and P2 recently reported for LiEuW{sub 2}O{sub 8} and LiYW{sub 2}O{sub 8} were not observed.

• OSTI ID: 21580194
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 8 Vol. 184; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
COHERENT SCATTERING
CRYSTAL LATTICES
CRYSTAL STRUCTURE
DIFFRACTION
ELEMENTS
METALS
MINERALS
OXIDE MINERALS
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
RARE EARTHS
REFRACTORY METAL COMPOUNDS
SCATTERING
SPACE GROUPS
SYMMETRY GROUPS
TEMPERATURE RANGE
TEMPERATURE RANGE 0065-0273 K
TETRAGONAL LATTICES
TRANSITION ELEMENT COMPOUNDS
TRICLINIC LATTICES
TUNGSTATES
TUNGSTEN COMPOUNDS
WOLFRAMITE
X-RAY DIFFRACTION