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The crystal structures of Rb3Sb2Br9 (I), Rb3Sb2I9 (II), Rb3Bi2Br9 (III), Rb3Bi2I9 (IV), and Tl3Bi2Br9 (V) are determined by single crystal XRD.

CuTe is prepared from the elements by annealing at 470 K for 24 d and characterized by single crystal XRD, HRTEM, and DFT calculations.

Sub-micron and nanometer scaled particles of the title compounds are prepared by microwave-assisted metathesis reactions of LnCl3 (Ln: La, Pr, Nd) and Na2S2 or Na2S4 in DMF (microwaves, 160—220 °C, 20 min—24 h).

The title compounds are prepared from Ln2X3 (Ln: Gd—Tm, X: S, Se) and sulfur or selenium (3 GPa, 1193—1973 K, 360—2600 min) and characterized by powder and single crystal XRD.

Ternary lanthanum sulfide selenides LaS1.9-xSex (0 < x < 1.9) are prepared by reaction of the elements in a KBr flux (carbon crucibles, 850 °C, 7 d).

The title compounds are prepared by metathesis reactions of adequate amounts of LaCl3, Na2S2, and K2Se3 (850 °C, 7 d).

Dark red crystals of the title compounds are prepared by flux reactions of the elements in KBr (1070 K, 10 d) and by metathesis reaction of LnCl3 (Ln: Tb—Ho) and M2S2 (M: Na, K).

The title compound is prepared by reaction of the elements in an NaCl flux (La:S:Se = 1:1.9:0.1; glassy carbon crucible in a sealed silica tube, 850 °C, 7 d).

Lanthanum ruthenium carbide La3.65[Ru(C2)3] crystallizes hexagonal (P63/m) with a = 887.9(2) pm and c = 1606.8(6) pm, V = 1096.8(4)·106 nm3, and Z = 6. The crystal structure contains trigonal-planar Ru(C2)3 groups and lanthanum atoms, which form a partial structure of the chemical composition La3Ru(C2)3. Additional lanthanum atoms occupy hexagonal channels built by those carbon atoms of the C2 ligands, which are non-bonded to the central ruthenium atoms. The distribution of these lanthanum atoms along the c axis results in a threefold superstructure, which was refined as a commensurate modulated structure (P63/m (00g)s0, q = (0, 0, {}^1/{}_3)). Harmonic occupational and displacive modulation functions were used for the structure refinement. The structure converged to R1 = 4.9 % for all data (R1 = 2.6 % for the main reflections, R1 = 11.1 % for the 1st order satellite reflections). A small homogeneity range for this phase is predicted by total energy calculations using the PAW-GGA method (VASP). Chemical bonding analysis reveals that the C2 pairs are best described as acetylide C22– units.

Single crystals of KBaNbS4 have been prepared by the reaction of Nb with an in situ formed melt of K2S3, BaS, and S at 500 °C. Satellite reflections observed in X-ray diffraction experiments of these crystals indicate the presence of a one-dimensional lattice distortion. The modulated structure has been solved and refined from X-ray data using the superspace group approach. KBaNbS4 can be described in the (3 + 1)-dimensional superspace group Pnma(α00)0s0 with lattice parameters a = 9.187(1), b = 7.001(1), and c = 12.494(1) A and a modulation vector q = (0, 0.629(1), 0). In the structure the NbS4 tetrahedra are stacked along the a axis and show a slight tilting against each other. The K+ and Ba2+ ions follow this tilting, both are slightly shifted from their positions in the average structure. The modulation does not lead to a significant change in the coordination spheres of the metal atoms. The small effects of the modulation correspond to the relatively weak intensities of the satellite reflections. Results of temperature dependent X-ray investigations indicate that K+ librates at higher temperatures and the surrounding S2− anions follow this motion. With decreasing temperature the libration of K+ is reduced and the coordination geometry freezes under formation of an incommensurate modulation. The heavier Ba and Nb atoms are also affected by positional modulation of the substructure and accommodate to their environment.

Single crystals of LaSeTe2 have been prepared by reaction of the elements in a LiCl/RbCl flux at 970 K for seven days. Satellite reflections observed in diffraction experiments indicate the presence of an incommensurate lattice distortion, which is of the charge-density-wave (CDW) type. The modulated structure has been solved from X-ray data at 173, 293, and 373 K. LaSeTe2 crystallizes in the 3+1-dimensional orthorhombic superspace group Cmcm(00γ)s00 (No. 63.2) with lattice parameters of a = 4.295(1), b = 25.371(4), c = 4.306(1) A (173K), a = 4.297(1), b = 25.408(4), c = 4.309(1) A (293 K), and a = 4.309(1), b = 25.481(6), c = 4,321(1) A (373 K). The modulation vector q = (0, 0, 0.288) does not change over the temperature interval. Electron holographic investigations confirm the existence of the modulation and help to visualize the charge-density wave. (Less)