Crystal structure of LiLnW2O8 (Ln=lanthanides and Y): An X-ray powder diffraction study

Crystal structures that occur in LiLnW2O8 (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 I41/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 LiTbW2O8, 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 P1̄ and P2, recently reported for LiEuW2O8 and LiYW2O8, have not been observed in this series of compounds.