Superspace crystallography: a key to the chemistry and properties

Abstract

An overview is given of the recent advances in the field of modulated molecular and inorganic crystals with an emphasis on the links between incommensurability, intermolecular and interatomic interactions and, wherever possible, the properties of the materials. The importance of detailed knowledge on the modulated structure for understanding the crystal chemistry and the functional properties of modulated phases is shown using selected examples of incommensurate modulations in organic molecular compounds and inorganic complex oxides.

Tiling approach for the description of the sevenfold symmetry in quasicrystals

“…Our results may stimulate further research in various fields of generalized crystallography including scale and superspace crystallography [41][42][43][44][45]. We expect that our mathematical models will help researchers to better understand the ordering phenomena in soft matter and relating materials, to explain the appearance of anomalous symmetries in colloidal layers, and to design new types of photonic crystals, artificial solids, metamaterials, and so forth [46][47][48][49][50][51][52][53].…”

Small-angle neutron diffraction on the vortex lattice of Type II superconductors

“…A 30_ reorientation of this vortex lattice has been observed in a very low field of 200 Oe. This reorientation transition is first-order and reflect nonlocal effects [3].…”

“…These can affect everything from the smallest molecules to large macrocycles to frameworks. [1][2][3] Here we present a selection of the data that have made us want to scream when working in collaboration with the Chemists in Oxford.…”

A Review of Mechanoluminescence in Inorganic Solids: Compounds, Mechanisms, Models and Applications

“…The modulation can be a periodic displacement of atomic positions or a periodic occupation of atoms at a specific crystallographic site [34], which can be interpreted in terms of the compromise between competing distortion modes or electronic instabilities [281]. A noteworthy case is the incommensurate structure in melilite compounds.…”