Schustereit, TanjaMüller, Sabine L.Schleid, ThomasHartenbach, Ingo2014-10-202016-03-312014-10-202016-03-312011415781272http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-95846http://elib.uni-stuttgart.de/handle/11682/1449http://dx.doi.org/10.18419/opus-1432The rare-earth metal(III) ortho-oxomolybdates with the formula Ln0.667[MoO4] (Ln = Ce, Pr, Nd, and Sm) and defect scheelite-type structure crystallize in the tetragonal space group I41/a (a = 533–525, c = 1183–1158 pm) with four formula units per unit cell. The Ln3+ cations at Wyckoff position 4b exhibit a coordination sphere of eight oxygen atoms in the shape of a trigonal dodecahedron. The same site symmetry ( 4 ..) is observed for the tetrahedral oxomolybdate(VI) entities [MoO4]2–, since their central Mo6+ cation is situated at the 4a position. Due to this equal site multiplicity, the lanthanoid(III) cations have to be statistically under-occupied to maintain electroneutrality, thus a defect scheelite structure emerges. The partial structure of both the Ln3+ cations and the [MoO4]2– anions (if shrunk to their centers of gravity) can be best described as distorted diamond-like arrangements. Therefore, these two interpenetrating partial structures exhibit a similar setup as found in the zircon-type as well as in the NaTl-type structure.eninfo:eu-repo/semantics/openAccessLanthanoide , Scheelit , Kristallstruktur540MolybdateLanthanoids , Molybdate , Scheelite , Crystal Structurearticle2014-10-20