Hans Burzlaff

(C6H5CH2CH2NH3)2[CdCl4]

The title compound, bis(β-phenylethylammonium) tetrachlorocadmate, (C8H12N)2[CdCl4] crystallizes as a layer structure; the heavy atoms form a two-dimensional network of corner-connected octahedra, the organic cation being connected to the network through hydrogen bonding.

Bis(4-benzylpiperidinium) tetrachloromercurate

The title compound, (C 12 H 18 N) 2 [HgCl 4 ], contains a distorted tetrachloromercurate tetrahedron, with Hg-Cl distances ranging from 2.424(3) to 2.614 (2) A. Variations can be attributed to the presence of hydrogen bonding. The anions and cations are connected by N-H...Cl bonds, building a two-dimensional network.

Electron density distribution in Nd2−xCexCuO4−δ

Abstract The distribution of electron density in single crystals of Nd 2 CuO 4 and changes caused by Ce doping in Nd 2− x Ce x CuO 4−δ crystals have been studied using X-ray diffraction data. Investigations have been carried out on a non-doped sample of Nd 2 CuO 4 at 293 and 20 K, and on two crystals of Nd 2− x Ce x CuO 4−δ at 293 K. In the non-doped sample, the electron density distribution shows features characteristic at the copper atom in the Cu 2+ valence state and redistribution of the valence electrons of the Nd atom due to bonding. The substitution of Nd by Ce leads to a change in the valence state of Cu and changes the whole picture of the electron density.

Influence of Ce doping on the distribution of the electron density in Nd2−xCexCuO4−δ

Abstract Changes in the distribution of electron density in single crystals of Nd 2− x Ce x CuO 4−δ caused by Ce-doping have been studied using X-ray diffraction data. The substitution of Nd by Ce changes as the electronic state of Cu as the whole picture of the electron density in crystals.

On symmetry classes of crystal structures.

An open-ended classification scheme for crystal structures based on Wyckoff sets and affine normalizer groups is proposed. It is free of metrical and geometrical considerations. All structures of one structure type belong to the same symmetry class. An application is given for the Inorganic Crystal Structure Database (version 2, 2007).

Bis(piperidinium) Tetrachloromercurate

The title compound, (C 5 H 12 N) 2 [HgCl 4 ], contains piperidinium cations and tetrachloromercurate anions, which are connected by N-H...Cl bonds via the C11, C12 and C13 atoms into a two-dimensional network in the (101) plane through the origin. The Hg-Cl bond lengths lie between 2.431(3) and 2.515 (2) A.

1,3-Propanediammonium Tetrachloromercurate

The title compound, (C3H12N2)[HgCl4], contains layers of tilted corner-sharing chloromercurate octahedra, with Hg—Cl distances ranging from 2.397 (2) to 2.839 (2) A. These layers are interconnected by N—H⋯Cl bonds to the cations, building a three-dimensional network. The cation has a disordered propane chain.

Changes in the distribution of electron density in Nd2−xCexCuO4−y, x = 0.13 during cooldown

Abstract In a previous paper [1] we described the influence of Ce-doping on the distribution of the electron density in the HTSC-compound Nd 2− x Ce x CuO 4−δ . The main feature of the doping which appeared on the electron density maps is the rearrangement of the charge density at the Cu position. Also the formation of a strong positive charge density maximum at the Nd/Ce position could be observed. By cooling down the sample from 300 K to 25 K this maximum splits up. Further calculations to explain this behaviour have been carried out.

Redetermination of Bis(1,2-ethanediammonium) Dichloride Tetrachloromercurate(II)

The structure of the title compound, 2[C2H10N2]2+.2Cl−.HgCl42−, originally determined at 153 K [Wen et al., (1992). Inorg. Chim. Acta 193, 77–85] has been redetermined with room-temperature data. The discussion of the structure can be found in the original paper.

Preparation, structural and magnetic properties of electron-doped infinite-layer HTSC Sr1−xNdxCuO2−δ

Abstract We present our method of fabricating superconducting compounds of the infinite-layer structure Sr1−xNdxCuO2−δ with various doping concentrations. The samples undergo a high temperature-high pressure process and are then bulk superconductors without any further treatment. A slightly reducing atmosphere was necessary to get doped layer-phases. Refinement of the crystallographic data was done by a least squares method. The Tconset values are in the range of 36–41 K. The lower critical field Hc1ab(T=0) is extrapolated to 15 G, while magnetization cycles show extremely weak pinning behaviour. From photoemission data a considerably diminished Cu-O-hybridisation is found. The particular shape of partial Nd-valence band spectra for these compounds shows Nd to work as a trivalent dopant for divalent Sr.