Diffuse scattering and ordering in the short-range modulated paraelectric phase of sodium nitrite, NaNO₂

Contrary to the well known modulated structures with sharp satellite reflections, the diffraction pattern of a short-range modulated structure contains diffuse satellite reflections. The crystal structure of NaNO₂ above T_N = 437.7 K in the paraelectric phase is short-range modulated with remnants of distorted fragments of a sinusoidal modulation.

Evidence for differentiation in the iron-helicoidal chain in GdFe₃(BO₃)₄

The structure phase transition of GdFe(BO) is investigated. A single-crystal X-ray structure study is reported at room temperature and at T = 90 K. The low-temperature space group found is P3₁21.

Pseudoepitaxial transrotational structures in 14 nm-thick NiSi layers on [001] silicon

In this work we show that in a 14 nm-thick NiSi layer, the silicide lattice can three-dimensionally adapt to that of a [001]-oriented Si substrate by forming transrotational domains. The resulting structural properties are promising to improve the structural and electrical stability of very thin NiSi layers.

Extremely long period-stacking structure in the Sb–Te binary system

The crystal structures of Sb–Te compounds that are materials currently used for DVDs were investigated by powder X-ray diffraction using synchrotron radiation. Each structure is fundamentally a simple stacking structure, but the stacking period changes regularly with composition and becomes extremely long.

Reversible pressure-induced structure changes in turbostratic BN–C solid solutions

The crystallographic mechanism of the pressure-induced transformation of turbostratic graphite-like BN–C solid solutions at room temperature has been studied by Rietveld analysis and numerical modeling.

Searching the Cambridge Structural Database for polymorphs

An automated method to scan a total of over 325 000 small-molecule crystal structures in the Cambridge Structural Database for polymorphs is described. The results for 35 000 pairs of crystal structures are reported: 308 previously unknown individual polymorphs were identified.

A third blind test of crystal structure prediction

The findings of the third blind test of crystal structure prediction are presented and discussed in the context of the previous collaborations – CSP1999 and CSP2001.

Comparing hypothetical structures generated in the third Cambridge blind test of crystal structure prediction

Extended lists of the hypothetical crystal structures of two small semi-rigid molecules, submitted in the third Cambridge blind test of crystal structure prediction, were analyzed for completeness and correlation between energies.

Morphotropism: link between the isostructurality, polymorphism and (stereo)isomerism of organic crystals

Morphotropism (i.e. the non-crystallographic rotation of motifs) bridges the phenomena of isostructurality, polymorphism and (stereo)isomerism. Various forms of virtual and effective rotation of the common motifs, through either 90 or 180°, between chemically related structures, are presented.

Representing structural databases in a self-organizing map

A visualization of diversity in structural databases by mapping powder diffraction patterns in a two-dimensional self-organizing map is presented, including principles and applications.

Validation of a search technique for crystal structure prediction of flexible molecules by application to piracetam

A new approach to the crystal structure prediction of flexible molecules is described and illustrated using a `blind' prediction of a recently solved conformational polymorph of piracetam.

A structural study of new potent and selective antagonists to the A_2B adenosine receptor

The crystal structures of five new xanthinic derivatives acting as adenosine antagonists have been determined. Other molecules of known biological activity have been reported and compared, with the aim of understanding the structural features controlling their affinity capabilities and selectivity.

Energetic materials: α-NTO crystallizes as a four-component triclinic twin

The α-polymorph of the energetic material 5-nitro-2,4-dihydro-1,2,4,-triazol-3-one (NTO) crystallizes as a four-component triclinic twin (fourling). The twin laws are rationalized on the basis of the symmetry of a pseudo-orthorhombic superstructure and the molecular packing.

Bayesian methods for the conformational classification of eight-membered rings

A probabilistic model is used to group the eight-membered ring conformations using the intra-ring torsion angles. Hints about the interconversion pathways between conformations are also obtained.

In situ high-pressure crystallization and compression of halogen contacts in di­chloro­methane

The pressure-frozen structure of CH₂Cl₂ has been determined by single-crystal X-ray diffraction at 1.33 and 1.63 GPa, and the intermolecular electrostatic, halogen⋯halogen and H⋯halogen crystal cohesion forces have been analysed.