Introduction to the special issue on electron crystallography

The Guest Editors of the special issue, Joke Hadermann and Lukáš Palatinus, introduce the collection of papers.

Automated electron diffraction tomography – development and applications

Electron diffraction tomography, a potential method for structure analysis of nanocrystals, and, in more detail, the strategies to use automated diffraction tomography (ADT) technique are described. Examples of ADT application are discussed according to the material class.

Scanning transmission electron diffraction methods

Methods and applications for crystallographic mapping using scanning electron diffraction in the transmission electron microscope are reviewed.

Structure solution and refinement of metal-ion battery cathode materials using electron diffraction tomography

Electron diffraction tomography is optimally suited to determine the crystal structure of metal-ion battery cathode materials at different states of charge. Here the possibilities, hurdles and advantages compared to other techniques are discussed.

3D electron diffraction techniques

This a review of the different 3D electron diffraction techniques.

Methods for orientation and phase identification of nano-sized embedded secondary phase particles by 4D scanning precession electron diffraction

Numerical approaches have been developed to extract more than the dominant signal from stacks of scanning precession electron diffraction patterns. Nano-precipitates embedded in an Fe- or Al-based matrix have been properly identified with these techniques.

Specifics of the data processing of precession electron diffraction tomography data and their implementation in the program PETS2.0

PETS is a computer program for processing electron diffraction data. Its features include support for detailed analysis of precession electron diffraction data, serial electron crystallography data collected with or without precession, detailed analysis of frame orientation and data processing for dynamical structure refinement.

Inelastic scattering and solvent scattering reduce dynamical diffraction in biological crystals

Multiple, dynamical electron diffraction can be simulated by multislice calculations. However, experimental evidence indicates that these calculations overestimate dynamical diffraction. It is shown that ignoring bulk solvent scattering and inelastic scattering in calculations, results in overestimating dynamical effects.

Towards qu­antitative treatment of electron pair distribution function

A review of electron pair distribution function (ePDF) analysis is presented. A quantitative treatment of ePDF is demonstrated for a nanocrystalline anatase sample.

Structure analysis of materials at the order–disorder borderline using three-dimensional electron diffraction

Three-dimensional electron diffraction proves a powerful crystallographic method for the qualitative and quantitative analysis of defective features in nanocrystalline materials. An overview of most prominent studies of defect structures using three-dimensional electron diffraction is presented.

Ab initio determination of atomic structure of Zn–Zr precipitates in a Mg–Nd–Zn–Zr alloy

Zn–Zr precipitates in an Mg alloy are determined to be Zn₂Zr₃ with a primitive tetragonal structure (space group P4₂/mnm, lattice parameters a = b = 0.761 nm, c = 0.682 nm) using Z-contrast imaging.

Optical and structural characteristics of PMMA films doped with a new anisometric Eu^III complex

A new film material capable of transforming UV radiation into visible light was obtained from a new Eu^III anisometric complex with organic ligands in a polymethyl­methacrylate (PMMA) matrix and structurally characterized. From X-ray powder diffraction and small-angle scattering data, it is supposed that molecules of the Eu^III complex occur in the voids of the PMMA matrix and this is accompanied by the formation of a nanocrystalline phase.

High-temperature Fe oxidation coupled with redistribution of framework cations in lobanovite, K₂Na(Fe²⁺₄Mg₂Na)Ti₂(Si₄O₁₂)₂O₂(OH)₄ – the first titanosilicate case

High-temperature study of lobanovite from a heterophyllosilicate family revealed that the mineral undergoes iron oxidation coupled with deprotonation (starting at T > 450°C) followed by rearrangement of Fe and Mg cations within close-packed octahedral layers.

The structure and crystal chemistry of vernadite in ferromanganese crusts

Vernadite from ferromanganese crusts has mixed layered structures based on results from synchrotron X-ray diffraction, X-ray pair distribution function, and high-resolution transmission electron microscopy.

Influence of ligand positional isomerism on the molecular and supramolecular structures of cobalt(II)-phenyl­imidazole complexes

The impact of two flexible positional isomeric ligands (2- and 5-phenyl­imidazole) and of the coordinated inorganic anions (Cl⁻, I⁻, NO₃⁻, NCS⁻) on the stoichiometry/coordination and packing arrangement of eight new cobalt(II) complexes has been thoroughly studied.

Revisiting the structure of a synthetic somatostatin analogue for peptide drug design

The tertiary structure of a somatostatin analogue, octreotide, has been identified from polycrystalline precipitates at 2.85 Å resolution.

Accessing the rich carbon nitride materials chemistry by heat treatments of ammonium thio­cyanate, NH₄SCN

Carbon nitrides include functional materials and a range of carbon nitride products obtained from the pyrolysis of NH₄SCN is presented here.

Tennantite: multi-temperature crystal structure, phase transition and electronic structure of synthetic Cu₁₂As₄S₁₃

The structure of synthetic tennantite Cu₁₂As₄S₁₃ is investigated at various temperatures in the 90–293 K range. The refinements show significant disorder at high temperatures for the triangular coordinated copper atom and neighbouring site, and fixed atomic positions at low temperatures. One particle potential is used to describe the behaviour of atoms at these copper sites.

The incommensurately modulated structures of volcanic plagioclase: displacement, ordering and phase transition

The metastable incommensurate structure of basaltic plagioclase phenocryst varies with the composition and cooling rate of the host rock, which may enable scientists to quantitatively study the thermal history of volcanic rocks in new ways.

The role of multiple observations in small-molecule single-crystal service X-ray structure determination

The effect of varying the multiplicity of observations is explored in the context of varying acquisition time, detector binning, maximum resolution and completeness. The cost/benefit analysis suggests that, in the context of service analytical crystallography, seeking a high multiplicity of observations and including poor-quality data in a refinement do not significantly improve the result.

Structural variety of clofaziminium salts: effect of the counter-ion on clofaziminium conformation and crystal packing

The crystal packing of known and new clofaziminium salts is presented and a conformational comparison is made.

Pressure-dependent X-ray diffraction of the multiferroics RMn₂O₅

Powder X-ray experiments and density functional theory calculations have been performed on RMn₂O₅ multiferroics under high pressure to deduce the evolution of the exchange interactions with pressure and explain the effect of pressure on the multiferroic properties.

The novel borate Lu₅Ba₆B₉O₂₇ with a new structure type: synthesis, disordered crystal structure and negative linear thermal expansion

Lu₅Ba₆B₉O₂₇ crystallizes in a new structure type in space group C2/c. The structure is disordered: one of the B atoms is surrounded by six O atoms with partial occupancies of 0.5, and this is the first example of a borate where the partial occupancy of only the O atoms is observed. Its thermal expansion is highly anisotropic. The negative linear expansion is parallel to the planes of the largest number of [BO₃] triangles.

Topotactic, pressure-driven, diffusion-less phase transition of layered CsCoO₂ to a stuffed cristobalite-type configuration

A reconstructive, still diffusion-less and topotactic pressure-driven phase transition of CsCoO₂ is studied and an analysis of the transition pathway using ISODISTORT is presented.

Daliranite, PbHgAs₂S₅: determination of the incommensurately modulated structure and revision of the chemical formula

The modulated crystal structure of the mineral daliranite has been determined using 3D electron diffraction on nanocrystalline domains.

Interstitial defects in the van der Waals gap of Bi₂Se₃

The use of scanning transmission electron microscopy (STEM) and energy-dispersive X-ray spectroscopy uncovered interstitial defects with mainly Bi character in Bi₂Se₃. This finding is supported by precession electron diffraction tomography and density functional theory calculations. The electron beam used during the STEM experiment induced atomic displacements across and along the van der Waals gap, though climbing-image nudged elastic band calculations show that some paths could also occur spontaneously at room temperature.

From space group to space groupoid: the partial symmetry of low-temperature E-vanillyl oxime

The partial symmetry of low-temperature E-vanillyl oxime is analysed using space groupoids.

Structure change of monoclinic ZrO₂ baddeleyite involving softenings of bulk modulus and atom vibrations

Deformation of a sublattice composed of O atoms is related to compressional anomalies of baddeleyite: softenings of bulk modulus and atom vibrations.

Experimental and theoretical charge-density analysis of hippuric acid: insight into its binding with human serum albumin

The charge-density analysis of an important metabolite has been carried out using high-resolution X-diffraction data. The study of its electrostatic properties provides insight into its binding with human serum albumin.

An-Pang Tsai (1958–2019)

Obituary for An-Pang Tsai

Problems in Structural Inorganic Chemistry. Second edition