New insights into structural diversity of open-framework silicates inspired by the exploration of the Cs₂O–CaO–SiO₂ system

The structure of unique compound Cs₄Ca[Si₈O₁₉] reported recently by Kahlenberg [(2025), Acta Cryst. B81, 325–336] contributes to the broader understanding of structure–property relationships in open-framework silicates (as well as silicates with mixed octahedral–tetrahedral frameworks), with potential implications for ion-exchange, catalysis, and materials with tailored thermal expansion.

Structures of phospho­nitrides in light of the extended Zintl–Klemm concept

The extended Zintl–Klemm concept (EZKC), applied satisfactorily to rationalize the structures of aluminates and silicates, also accounts for the structures of ternary phospho­nitrides.

The role of the solvent molecule in the crystal packing arrangements of hydrated salts formed by ethacridine and fluoro­benzoic acids

Single-crystal X-ray diffraction is used to characterize the role of the solvent molecule in the crystal packing of three new hydrated salts formed from ethacridine and fluorobenzoic acids. The number of water molecules in the asymmetric unit determines the formation of distinct centrosymmetric supramolecular synthons: [⋯water⋯acid⋯]₂ and [⋯water⋯water⋯acid⋯]₂

Structural phase transitions, dehydration and decomposition of ammonium hypodiphosphates

Seven ammonium salts of hypodi­phospho­ric acid, H₄P₂O₆, are described in terms of their crystal structure, phase transitions, dehydration and decomposition using SC-XRD, variable-temperature µ-PXRD, differential scanning calorimetry and simultaneous thermogravimetry and differential thermal analysis.

Multidisciplinary study of thorium mobility: formation of turkestanite and steacyite analogues, and structural insights using an XRD-directed microcrystal preparation technique

A novel focused ion beam and scanning electron microscope-based technique has been developed for mounting microcrystals on carbon fibre, making them immediately compatible with single-crystal X-ray diffraction. This method has been successfully applied to studying the crystal chemistry of a synthetic Th-bearing, Na analogues of turkestanite and steacyite, and should prove suitable for the study of other micro-sized phases.

A linear/quadratic order parameter coupling description of the Verwey transition in magnetite, Fe₃O₄

The change in symmetry at the Verwey transition in magnetite puts it in an important class of phase transitions with linear/quadratic coupling between two separate order parameters. We use group theory to characterize the form of the coupling between charge order and an electronic instability, and test the model with structural data.

Call for papers for special issue: Crystal Growth and Related Characterization

Symmetry Relationships between Crystal Structures. Second edition