The Crystal Structure of the New REE–Te Oxychlorides: NdTe2O5Cl and GdTe2O5Cl

The title compounds were 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) Å, 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 [LnTe2O+5] and [Cl−] layers (X31 structure). Related structures and the nature of cation ordering in the metal–oxygen layers are discussed.