Abstract. The compounds Li 8 EN 2 with E = Se, Te were obtained in form of orange microcrystalline powders from reactions of Li 2 E with Li 3 N. Single crystal growth of Li 8 SeN 2 additionally succeeded from excess lithium. The crystal structures were refined using single-crystal X-ray diffraction as well as X-ray and neutron powder diffraction data (I4 1 md, No. 109, Z = 4, Se: a = 7.048(1) Å, c = 9.995(1) Å, Te: a = 7.217(1) Å, c = 10.284(1) Å). Both compounds crystallize as isotypes with an anionic substructure motif known from cubic Laves phases and lithium distributed over four crystallographic sites in the void space of the anionic framework. Neutron powder diffraction pattern recorded in the temperature range from 3 K to 300 K and X-ray diffraction patterns using synchrotron radiation taken from 300 K to 1000 K reveal the structural stability of both compounds in the studied temperature range until decomposition. Motional processes of lithium atoms in the title

A redetermination of the structure of`La 32.66 Fe 11 S 60 ' in the trigonal space group R3m led to the new formula La 52 Fe 12 S 90 and to a rede®nition of the structure type. In the structure, the Fe 2+ cations occur in Fe 2 S 9 dimers of face-sharing octahedra (with 3m symmetry). The dimers are linked by face-and vertex-sharing bi-and tricapped LaS 6 trigonal prisms (with m symmetry) to form a three-dimensional network containing two types of cuboctahedral cavities. The larger cavities remain empty, while the smaller ones accommodate alternative sites for disordered La 3+ cations. CommentIn a search for materials with interesting magnetic properties, we have begun a reinvestigation of the R±Fe±S system (R = rare earth metal). With the larger rare-earth metals, phases of three different compositions are formed, viz. R 2 Fe 2À S 5 (R = La, Ce and Pr), R 3 Fe 2À S 7 (R = La, Ce, Pr and Nd) and R 52 Fe 12 S 90 (R = La, Ce, Pr and Nd) (Collin et al.

The ternary nitridochromate Ce 2 [CrN 3 ] (orthorhombic Immm, a = 378.56(1) pm, b = 340.88(2) pm, c = 1251.27(4) pm) was synthesized in single phase form from the binary nitrides utilizing the decomposition of CrN to Cr 2 N. Magnetic susceptibility measurements * Prof. Dr. R. Niewa

The cubic Perovskite (Ca2EuN0.75)Sn was synthesized in a solid state reaction from EuN, Ca, and Sn. Nitrogen deficiency and Ca/Eu disorder is in agreement with results from chemical analysis, X‐ray diffraction, and Mössbauer spectroscopy. Magnetic susceptibility measurements as well as Mössbauer and X‐ray absorption spectroscopy indicate a mixed‐valent situation with di‐ and trivalent europium, apparently situated together with calcium on one crystallographic site. According to electrical resistivity measurements the title compound represents a heavily doped semiconductor.

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Metal. -The new compounds (La1-xCa3+xN1-x/3)Bi2 (x= 0.10, 0.05, 0.00), (Ce0.7Ca3.3N0.9)Bi2, and (PrCa3N)Bi2 are characterized by powder X-ray and neutron diffraction, magnetic susceptibility, and electrical resistivity measurements. The compounds crystallize with the K2[NiF4]-type structure in the space group I4/mmm with Z = 2. The La and Ce compounds exhibit small homogeneity ranges and a nitrogen deficiency. For (PrCa3N)Bi2 no indications for a significant homogeneity range or nitrogen deficiency are observed. All the samples are heavily doped semiconductors. -(GAEBLER, F.; BRAEUNLING, D.; SENYSHYN, A.; SCHNELLE, W.; NIEWA*, R

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Black crystals of La 53 Fe 12 S 90 X 3 (X ϭ Cl, Br, I) were synthesized from La 2 S 3 and FeS in a reactive LaX 3 flux at 1320 K. The structures were determined by single-crystal X-ray diffraction. The compounds are isostructural, crystallizing in the rhombohedral space group R3m with Z ϭ 1 (La 53 Fe 12 S 90 Cl 3 : a ϭ 14.0154 (7), c ϭ 21.888(1) Å , V ϭ 3723.5(3) Å 3 ; La 53 Fe 12 S 90 Br 3 : a ϭ 14.0048(9), c ϭ 22.040(2) Å , V ϭ 3743.6(4) Å 3 ; La 53 Fe 12 S 90 I 3 : a ϭ 13.9805(8), c ϭ 22.108(2) Å , V ϭ 3742.2(4) Å 3 ). The structure adopted is a stuffed variant of the La 52 Fe 12 S 90 structure type.[Fe II 2 S 9 ] dimers of face-sharing octahedra are linked by face-and vertex-sharing bi-or tri-capped [La III S 6ϩn ] trigonal prisms, forming a three-dimensional framework containing cuboctahedral cavities of two sizes. The larger cavities, which remain empty in the struc- EinleitungDie Thioferrate der Lanthanoiden zeichnen sich durch strukturelle Vielfalt, Gemischtvalenz und ausgeprägte Defektchemie sowie interessante magnetische Eigenschaften aus. Letztere resultieren in erster Linie aus der Austauschwechselwirkung der magnetischen Momente der Eisenkationen. Die Frage, in welchem Umfang diese magnetischen Kopplungen durch Seltenerdelemente (Ln) mit ungepaarten Elektronen beeinflusst werden können, führte uns zur Untersuchung der ternären Systeme LnϪFeϪS. Für die größeren Lanthanoiden sind aus der Literatur Phasen der Zusammensetzungen Ln 2 Fe 2Ϫδ S 5 (Ln ϭ La, Ce, Pr), Ln 3 Fe 2Ϫδ S 7 (Ln ϭ La, Ce, Pr, Nd) und Ln 52 Fe 12 S 90 (Ln ϭ La, Ce, Pr, Nd) bekannt [1Ϫ3]. Die zugehörigen Kristallstrukturen enthalten [FeS n ]-Polyeder, die entweder isoliert 107 ture of La 52 Fe 12 S 90 , are filled by halide ions in La 53 Fe 12 S 90 X 3 . The smaller cavities accommodate numerous sites for disordered lanthanum cations, modelling a network of diffusion pathways through the structure. An analogous picture is obtained from the calculation of the periodic nodal surface (PNS): The PNS separates a labyrinth containing the framework atoms from a labyrinth containing the mobile lanthanum cations. Molecular dynamic simulations confirm a strong coupling between the motions of the mobile lanthanum ions and the neighbouring sulfide ions.