Structure of pyrrhotite 5C (Fe₉S₁₀)

An average statistical structure is presented for pyrrhotite 5C. An order–disorder structure description is proposed for the intermediate pyrrhotites of which 5C is an end member.

Octahedral tilting in Pb-based relaxor ferroelectrics at high pressure

Anti-phase octahedral tilts are shown to be an essential structural feature of the high-pressure phase of both stoichiometric and heavily Ba-doped PbSc_0.5Ta_0.5O₃ relaxor ferroelectrics with the perovskite structure type.

X-ray atomic orbital analysis of 4f and 5d electron configuration of SmB₆ at 100, 165, 230 and 298 K

Electron density in SmB₆ single crystals was measured at 100, 165, 230 and 298 K. The electron configuration of 2p of B, and 4f and 5d of Sm analysed by X-ray atomic orbital (XAO) explains well the observed electron density.

On the accurate bond-valence parameters for the Sb³⁺/O²⁻ ion pair

The improved values of the bond-valence parameters for the Sb³⁺/O²⁻ ion pair, r₀ = 1.927 Å and b = 0.446 Å, have been deduced from the crystal structures of the α and β polymorphs of Sb₂O₃ and from the set of precisely determined complex structures containing [Sb³⁺O_n] coordination shells.

Symmetry analysis of extinction rules in diffuse-scattering experiments

The symmetry analysis of extinction rules in diffuse scattering is extended and applied to structure-dependent scattering data associated with `disordered' materials.

Persistence of the stereochemical activity of the Bi³⁺ lone electron pair in Bi₂Ga₄O₉ up to 50 GPa and crystal structure of the high-pressure phase

The structural compression of Bi₂Ga₄O₉ was determined between 0 and 50 GPa across the high-pressure phase transition at 16 GPa from single-crystal X-ray diffraction and quantum mechanical calculations. The stereochemical activity of the lone electron pair of Bi persists up to the highest pressure.

Towards a generalized vision of oxides: disclosing the role of cations and anions in determining unit-cell dimensions

Theoretical calculations of the electron-localization function show that, at the volumes of the two CaO phases (rocksalt and CsCl type), the parent Ca structures (fcc: face-centred cubic; sc: simple cubic) exhibit charge-concentration zones which coincide with the positions occupied by the O atoms in their oxides. For the first time, the structure type, dimension and topology of CaO and BaSnO₃ are explained in univocal physical terms.

Determination of zinc incorporation in the Zn-substituted gallophosphate ZnULM-5 by multiple wavelength anomalous dispersion techniques

Synchrotron X-ray data collection at 11 wavelengths has allowed precise estimation of the zinc partial substitution at particular gallium sites in the gallophosphate ZnULM-5. A thorough exploration and comparison of available methodology is given, including the use of the CCP4 program suite, SHELXL and JANA2006. The heteroatom substitution is probably due to specific site relaxation.

Structures of relevant ammonium salts in fertilizers

The crystal structures of two double salts of ammonium nitrate and ammonium sulfate are reported, as well as their application in the Rietveld quantification of nitrosulfate fertilizers.

Charge-density analysis of the ground state of a photochromic 1,10-phenanthroline zinc(II) bis­(thiolate) complex

The experimental and theoretical charge densities in a photochromic light-emitting Zn complex indicate charge transfer to the phenanthroline ligand can originate from either thiolate ligand. The proper treatment of the Zn atom in charge-density analysis is described in detail.

Polymorphism in the nitrate salt of the [Mn(acetyl­acetonate)₂(H₂O)₂]⁺ ion

Four polymorphic forms of [Mn(acac)₂(H₂O)₂]NO₃·H₂O are described. Lattice-energy calculations have been carried out to compare the stabilities of the polymorphs.

Bond lengths in organic and metal-organic compounds revisited: X—H bond lengths from neutron diffraction data

Mean X—H bond lengths for organic X = C, N, O, B and for a variety of terminal and homometallic bridging transition-metal hydrides are derived from the increased volume of neutron diffraction data now available in the Cambridge Structural Database. Revised default normalization distances for use in deformation density and hydrogen-bond studies are proposed for C—H, N—H and O—H bonds.

Reversible phase transition of pyridinium-3-carboxylic acid perchlorate

The reversible phase transition induced by temperature in pyridinium-3-carboxylic acid perchlorate was detected by differential scanning calorimetry, dielectric measurement and variable-temperature X-ray single-crystal diffraction analysis.

The lines-of-force landscape of interactions between molecules in crystals; cohesive versus tolerant and `collateral damage' contact

Intermolecular energies in organic crystals are classified with respect to strength and attractive or repulsive character. Energies provide a much better landscape than just intermolecular distances.