Pervasive approximate periodic symmetry in organic P1 structures

The packing in all the organic, P1, R ≤ 0.050 structures in the 2019 release of the Cambridge Structural Database have been examined carefully; 86% of the reliable Z > 1 structures and 72% of the reliable Z = 1 structures of symmetric mol­ecules have approximate symmetry that is periodic in n dimensions, n = 3, 2, or, occasionally, 1.

Synthesis, chiral crystal structure, and magnetic properties of Ba₃Ga₂O₅Cl₂

Ba₃Ga₂O₅Cl₂, synthesized by solid-state reaction in air, is isostructural with Ba₃Fe₂O₅Cl₂, with the Ga³⁺ ions coordinated by O atoms and forming GaO₄ tetra­hedra. Magnetization measurements indicate tem­per­ature-independent diamagnetic behavior.

Formation and crystallization of TiO₂ nano­structures on various surfaces

A comparative study of the synthesis of TiO₂ nanorods on several surfaces is presented. It is found that pre-annealed Si/TiN/Ti substrate provides a seed layer for the aligned growth of TiO₂ nanorods, therefore, it is the optimal choice to achieve highly aligned TiO₂ nanorods.

Insights into isostructural and non-isostructural crystals of esters of oleanolic acid and its 11-oxo derivatives

The isostructural and non-isostructural crystals of oleanolic and glycyrrhetinic acid esters share a common building block, which is the dimer of head-to-tail arranged molecules.

Role of lone-pair electron localization in temperature-induced phase transitions in mimetite

The monoclinic-to-hexagonal phase transition in mimetite Pb₅(AsO₄)₃Cl was investigated by in situ temperature-dependent single crystal X-ray diffraction combined with ab initio molecular dynamics simulations.

The bond valence model as a prospective approach: examination of the crystal structures of copper chalco­genides with Cu bond valence excess

Bond valence analysis has been applied to various copper chalco­genides where the formal valence of copper exceeds 1. The copper bond valence excess is balanced by a bond valence deficit of the ligand, which corresponds to one ligand electron in excess per formula unit. This permits a crystal–chemical representation of the copper–ligand bonds that control the metallic state.

Resolving the structure of V₃O₇·H₂O and Mo-substituted V₃O₇·H₂O

This work provides detailed crystal structure data for V₃O₇·H₂O. Furthermore, it gives insight into Mo-substituted V₃O₇·H₂O.

Analytic description of nanowires II: morphing of regular cross sections for zincblende- and diamond-structures to match arbitrary shapes

Setting out from König & Smith (2021), we present an analytic morphing of zincblende- and diamond-structure nanowire (NWire) cross sections to arbitrary convex shapes as encountered in experiment. We predict the NWire atoms, bonds between these atoms and NWire interface bonds, plus characteristic lengths and area of the NWire cross sections. Cross section areas, ratios of internal bonds per NWire atom enable an interpretation of any spectroscopic NWire data. Our algorithms include a radial dependence of the NWire unit-cell parameter and can be applied to multi-core-shell NWires where NWire layers can be morphed independently from each other.

Analytical description of nanowires III: regular cross sections for wurtzite structures

Setting out from König & Smith [Acta Cryst. (2019), B75, 788–802; Acta Cryst. (2021), B77, 861], we present analytic descriptions of regular wurtzite-structure nanowire (NWire) cross sections, focusing on the underlying geometric–crystallographic definitions and the associated number theory. We predict the NWire atoms, bonds between these atoms and NWire interface bonds, characteristic lengths and cross section area for a periodic NWire slab. These parameters present fundamental tools to interpret any spectroscopic data which depend on the diameter and cross section shape of NWires.

Structure stabilization effect of vacancies and entropy in hexa­gonal WN

The structural stability of hexa­gonal tungsten mono­nitride (WN) has been studied combining scanning transmission electron microscopy and first-principles calculations. The results show that the WC-type WN with vacancies of 6∼8 at% is more stable than the previously proposed MnP-type and NiAs-type structures.

The tetrel bonding role in supramolecular aggregation of lead(II) acetate and a thio­semi­carbazide derivative

Reported here is a new Pb^II coordination complex [PbLOAc], which was readily synthesized from a mixture of Pb(OAc)₂·3H₂O and 1-(pyridin-2-yl)benzyl­idene-4-phenyl­thio­semicarbazide (HL). The supramolecular structure of the obtained complex is constructed through the Pb⋯O and Pb⋯S tetrel bonds and other non-covalent interactions, which were validated by theoretical calculations.

Formation of contact and multiple cyclic cassiterite twins in SnO₂-based ceramics co-doped with cobalt and niobium oxides

The formation of contact and cyclic cassiterite twins during crystal growth is controlled by oriented nucleation of SnO₂ domains on nanosized grains of structurally related cobalt–niobium oxide phases.

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