Crystallography of γ′-Fe₄N formation in single-crystalline α-Fe whiskers

The crystallography and mechanism of the early stages of the formation of cubic primitive γ′-Fe₄N in single-crystal α-Fe whiskers during gaseous nitriding were investigated by electron microscopy and electron backscatter diffraction. The α–γ′ phase transformation could be observed under simplified conditions owing to the lack of geometric constraints for the transformation.

Dynamical X-ray diffraction imaging of voids in dislocation-free high-purity germanium single crystals

White beam X-ray topography has been performed to provide direct evidence of micro-voids in dislocation-free high-purity germanium single crystals. A general method is proposed to verify the presence of voids for any crystalline material of high structural perfection.

Dark-field electron holography as a recording of crystal diffraction in real space: a comparative study with high-resolution X-ray diffraction for strain analysis of MOSFETs

A detailed theoretical and experimental comparison of dark-field electron holography and high-resolution X-ray diffraction is performed. Both techniques are applied to measure elastic strain in an array of metal–oxide–semiconductor field-effect transistors (MOSFETs) and the role of the geometric phase is emphasized.

Defining the hematite topotaxial crystal growth in magnetite–hematite phase transformation

A growth model of hematite crystals derived from magnetite–hematite phase transformation is determined from a new orientation condition.

A new approach to phason disorder for a decagonal quasicrystal: the moment series expansion of the tiling distribution function for AlCuRh

This paper reports the application of the moment series expansion of the characteristic function of the distribution associated with the geometric part of the structure factor to model phason disorder in the structure refinement of the decagonal quasicrystal AlCuRh. The main result is that combining a new approach to phasons with the standard Gaussian Debye–Waller formula gives better refinement results and a finer atomistic model of quasicrystals, based on the decagonal AlCuRh system.

A laboratory transmission diffraction Laue setup to evaluate single-crystal quality

A laboratory Laue transmission setup has been developed to evaluate single-crystal quality in extended specimens. The method combines a compact high-energy setup, a general indexing algorithm and a forward model. Orientation mapping and parasite grain detection can be achieved by scanning a part in the plane perpendicular to the beam.

Ptychographic X-ray speckle tracking with multi-layer Laue lens systems

Simultaneous wavefront metrology and sample projection imaging with multi-layer Laue lenses using the ptychographic X-ray speckle tracking technique is described. Results from three experiments are presented.

Iterative X-ray spectroscopic ptychography

Spectroscopic ptychography is a powerful technique to determine the chemical composition of a sample with high spatial resolution. This paper presents a novel algorithm to iteratively solve the spectroscopic blind ptychography problem.

Pulse-to-pulse wavefront sensing at free-electron lasers using ptychography

Understanding the wavefront of ultra-bright and ultra-short pulses of X-ray free-electron lasers is both important and challenging. A method based on ptychography that can retrieve full high-resolution complex-valued wave functions of individual pulses is presented.

PtyNAMi: ptychographic nano-analytical microscope

The ptychographic nano-analytical microscope (PtyNAMi) is designed for in situ/operando high-resolution imaging in two and three dimensions with high sensitivity and structural, elemental, chemical and electronic contrast.

Effect of 2,4-di­nitrophenol dye doping on tris­thioureazinc(II) sulfate single crystals: a potential nonlinear optical material

The effect of 2,4-dinitrophenol dye doping on tristhioureazinc(II) sulfate bulk single crystals has been studied with regard to their structural, mechanical, thermal, electrical and optical properties for nonlinear optical device applications.

In situ temperature profile measurements with high-energy X-rays as a probe of optical floating zone crystal growth environment

A new synchrotron-compatible furnace for simulating the environment inside an optical floating zone furnace is described. It is shown that temperature profiles within heated rods can be determined from in situ synchrotron diffraction data, and that these measured profiles can be reproduced with a four-component heat-transfer model.

Assessment of structure factors for analysis of small-angle scattering data from desired or undesired aggregates

Seven small-angle scattering structure factors are presented, including one novel structure factor. It is demonstrated how the structure factors are best applied to describe aggregation processes or to take scattering from undesired aggregates into account.

Retrieving the configuration of grain boundary structure in polycrystalline materials by extraordinary X-ray reflection analysis

Synchrotron X-ray diffraction measurements performed on Mg samples allowed the retrieval of preferred configurations of grain boundary interfaces through the observation of weak diffraction peaks located between fundamental reflections. Kinematical simulations verifying possible interface structures established the correspondence of the non-bulk peaks to grain boundary interfaces that may be less energetic than the usually investigated twin-plane symmetric conditions.

Predicting the available work from deformation-induced α′′ martensite formation in metastable β Ti alloys

The effect of applied stress state and β crystal orientation on available work from β-to-α′′ martensite formation in metastable β Ti alloys is analysed. Predictions based on an available work criterion show a strong effect of stress and crystal orientation, and consequences for forming processes and typical β textures are discussed.

Real-time tracking of the self-assembled growth of a 3D Ge quantum dot lattice in an alumina matrix

Real-time X-ray scattering reveals the growth of 3D correlated quantum dots in situ during ion beam deposition.

New method to measure domain-wall motion contribution to piezoelectricity: the case of PbZr_0.65Ti_0.35O₃ ferroelectric

A new single-crystal X-ray diffraction method and data analysis framework have been developed and implemented for the separation of intrinsic and domain-wall-motion contributions to the piezoelectric effect in functional ferroelectric materials. The technique is applied for the elucidation of the mechanism of piezoelectricity in a single crystal of the ferroelectric PbZr_0.65Ti_0.35O₃.

Viscous-medium-based crystal support in a sample holder for fixed-target serial femtosecond crystallography

A viscous-medium-based crystal support in a sample holder has been developed for fixed-target serial crystallography.

Resolving pseudosymmetry in tetragonal ZrO₂ using electron backscatter diffraction with a modified dictionary indexing approach

A modified dictionary indexing method is proposed to resolve pseudosymmetry in electron backscatter diffraction. The method is applied to simulated and experimental data sets of tetragonal ZrO₂ and demonstrated to correctly resolve pseudosymmetry.

A new parafocusing paradigm for X-ray diffraction

A novel approach to parafocusing X-ray diffraction with an annular incident beam is demonstrated. Proof of principle is achieved via a theoretical approach, simulations and experiments, demonstrating significantly higher intensity scattering when compared with conventional Bragg–Brentano geometries, but without the need for flat-specimen approximations.

X-ray characterization of physical-vapor-transport-grown bulk AlN single crystals

AlN single crystals grown by physical vapor transport have been analyzed by X-ray methods to evaluate dislocation types, densities and spatial distribution within the crystal. Potential changes of the AlN crystal quality during growth, both within the axial growth direction and within lateral expansion areas, have been investigated.

Complex modeling for the qu­antification of nanoscale disorder using genetic algorithms, density functional theory and line-profile analysis

Complex modeling is used for local and average atomic structure, nanostructure and microstructure quantification of an Au_0.25Cu_0.75 alloy. This approach is generalizable and should be extensible to other disordered systems, allowing for quantification of localized structure deviations.

From atoms to bonds, angles and torsions: mol­ecular metrics from crystal space, and two Excel implementations

Algebraic, vector and matrix methods (including metric matrices) for the calculation of molecular bond lengths, bond angles and bond torsion angles in crystal or direct space, using fractional or Cartesian coordinates, are described. Two live Excel implementations of the methods are provided, in which the reader may introduce their own coordinate data for automatic calculation.

GIWAXS-SIIRkit: scattering intensity, indexing and refraction calculation toolkit for grazing-incidence wide-angle X-ray scattering of organic materials

A software package is described for grazing-incidence wide-angle X-ray scattering geared towards weakly ordered materials, with functionality including scattering intensity normalization/uncertainty estimation, scattering pattern indexing and refractive shift correction.

EDDIDAT: a graphical user interface for the analysis of energy-dispersive diffraction data

EDDIDAT is a program that provides a graphical user interface for the evaluation of energy-dispersive X-ray diffraction data with the focus on depth-resolved residual stress analysis.

Chirok: a post-refinement tool to analyse absolute structure

Chirok is a new tool for a post-refinement analysis of absolute structures. It is based on the fit of a statistical distribution of Parsons quotients with various peak functions.

X-Seed 4: updates to a program for small-molecule supramolecular crystallography

X-Seed is still in use after two decades, during which time a number of enhancements have been implemented. It mainly serves as a graphical user interface for SHELX and POV-Ray, and facilitates exploration of crystal packing.

SAS-cam: a program for automatic processing and analysis of small-angle scattering data

SAS-cam is an automated data analysis pipeline, developed to meet the high-throughput operation requirements of synchrotron-facility-based small-angle scattering.

MrPIXEL: automated execution of Pixel calculations via the Mercury interface

A program is described that enables the energetics of crystal packing to be analysed quickly and easily through a user interface, using Pixel, Python scripts and the widely known visualizer Mercury.

In situ monitoring of hydrothermal reactions by X-ray diffraction with Bragg–Brentano geometry

A feasibility study is carried out of an autoclave chamber for in situ X-ray diffraction experiments under hydrothermal conditions. Quartz dissolution and tobermorite formation are monitored on conventional laboratory X-ray diffractometers.

Professor Dr Dirk Feil (1933–2020)