The crystal structure of the new REE-Te oxychlorides: NdTe₂O₅Cl and GdTe₂O₅Cl

The title compounds mere synthesized and their crystal structures were determined by powder X-ray diffraction methods. Both phases are tetragonal and crystallize in space group P4/mmm, NdTe2O5Cl with cell constants a = 4,0373(1), c = 8.7912(3) Angstrom, and GdTe2O5Cl a = 3,9611(2), c = 8.4043(8), Z = 1, These oxychlorides adopt layered structures belonging to the family of Sillen phases and are built of alternating [LnTe(2)O(5)(+)] and [Cl-] layers (X-1(3) structure), Related structures and the nature of cation ordering in the metal-oxygen layers are discussed. (C) 1999 Academic Press.