This research showcases the capabilities of dark-field X-ray microscopy (DFXM), a three-dimensional imaging method for nanostructures, in characterizing novel epitaxial gallium nitride (GaN) layers grown on GaN/AlN/Si/SiO2 nano-pillars, with implications for optoelectronics. Due to the SiO2 layer softening at the GaN growth temperature, the nano-pillars facilitate the coalescence of independent GaN nanostructures into a highly oriented film. On different types of nanoscale samples, DFXM was shown to produce extremely well-oriented lines of GaN (standard deviation of 004), alongside highly oriented material within zones spanning up to 10 square nanometers. This growth approach demonstrated promising results. At a macroscopic level, high-intensity X-ray diffraction shows that the coalescence of GaN pyramids induces misorientation of the silicon within nano-pillars, signifying that the intended growth mechanism includes pillar rotation during the coalescence. This growth strategy, crucial for micro-displays and micro-LEDs that necessitate minuscule, high-quality GaN islands, is impressively demonstrated by these two diffraction techniques. It also offers a novel avenue to enhance our understanding of optoelectronically essential materials at the highest possible spatial resolution.

The pair distribution function (PDF) analysis is instrumental in materials science for interpreting the intricate atomic-scale structural details. Unlike X-ray diffraction-based PDF analysis, PDF analysis derived from electron diffraction patterns (EDPs) using transmission electron microscopy facilitates high spatial resolution structural determination for specific sites. The current work introduces a new software tool capable of handling both periodic and amorphous structures, effectively addressing the practical difficulties of calculating PDFs from EDPs. Key to this program's capabilities is accurate background subtraction, achieved through a nonlinear iterative peak-clipping algorithm, coupled with automatic conversion of diverse diffraction intensity profiles into a PDF format, all without requiring any external software. Furthermore, the present research investigates the consequences of background subtraction and the elliptical distortion of EDPs on PDF profiles. The EDP2PDF software's reliability makes it suitable for analyzing the atomic structure of crystalline and non-crystalline substances.

The critical parameters for thermal treatment, pertaining to template removal in an ordered mesoporous carbon precursor produced via a direct soft-templating procedure, were revealed through the utilization of in situ small-angle X-ray scattering (SAXS). Dynamic SAXS data, tracked over time, demonstrated the structural characteristics: lattice parameter of the 2D hexagonal structure, diameter of the cylindrical mesostructures, and a power-law exponent related to interface roughness. Moreover, the separate evaluation of Bragg and diffuse scattering components within the integrated SAXS intensity provided detailed insights into the changes in contrast and the ordered structure of the pore lattice. Five specific regions of heat treatment were defined and discussed, revealing the governing procedures and reactions. The relationship between temperature, the O2/N2 ratio, and the resultant structure was investigated, and suitable parameter ranges for template removal were identified, ensuring minimal matrix disruption. The findings reveal the optimal temperature range for the process's final structure and controllability to be between 260 and 300 degrees Celsius, using a gas flow that incorporates 2 mole percent oxygen.

Using neutron powder diffraction, the magnetic order of synthesized W-type hexaferrites with diverse Co/Zn ratios was investigated. SrCo2Fe16O27 and SrCoZnFe16O27 exhibited a planar (Cm'cm') magnetic arrangement, in contrast to the uniaxial (P63/mm'c') ordering characteristic of SrZn2Fe16O27, a common feature of most W-type hexaferrites. Magnetic ordering in each of the three scrutinized samples exhibited non-collinear terms. A commonality exists between the non-collinear terms, present in the planar ordering of SrCoZnFe16O27, and the uniaxial ordering within SrZn2Fe16O27, suggesting a potential impending alteration of the magnetic framework. Analysis of thermomagnetic data revealed magnetic transitions at 520 and 360 Kelvin for SrCo2Fe16O27 and SrCoZnFe16O27 respectively, while Curie temperatures were found at 780K and 680K respectively. No transitions were found in SrZn2Fe16O27, only a Curie temperature of 590K. The sample's Co/Zn stoichiometry is a critical factor in the fine-tuning of the magnetic transition.

Orientation relationships, either calculated or measured, represent the connection between the crystallographic orientations of parent grains and those of their child grains in polycrystalline materials undergoing phase transformations. A new approach to orientation relationship (OR) analysis is presented in this paper, which addresses (i) OR estimation, (ii) the adequacy of a single OR for the given data, (iii) the common parentage of a set of children, and (iv) the reconstruction of a parent structure or grain boundaries. BGJ398 Within the crystallographic framework, this approach expands upon the well-established embedding technique for directional statistics. Precise probabilistic statements are generated by a method that is inherently statistical. Explicit coordinate systems and arbitrary thresholds are both eschewed.

The importance of precisely measuring the (220) lattice-plane spacing of silicon-28, achieved via scanning X-ray interferometry, lies in its role in defining the kilogram by counting 28Si atoms. The supposition is that the measured lattice spacing reflects the bulk property of the unstrained crystal which constitutes the interferometer analyzer. Studies employing analytical and numerical methods to investigate X-ray propagation in bent crystals suggest that the measured lattice spacing might be connected to the surface of the analyzer. In order to validate the outcomes of these studies and to aid experimental studies utilizing phase-contrast topography, a complete analytical framework is developed for a triple-Laue interferometer whose splitting or recombining crystal is bent.

Titanium forgings commonly display microtexture heterogeneities as a result of the specific thermomechanical processing employed. Cloning and Expression Vectors Macro-zones, as they are also known, can extend to millimeters in length, with grains exhibiting a comparable crystallographic alignment, thereby reducing resistance to crack propagation. Since the link between macrozones and diminished cold-dwell-fatigue performance of rotating components in gas turbine engines was confirmed, efforts have been proactively dedicated to the classification and detailed characterization of macrozones. For qualitative macrozone characterization, the electron backscatter diffraction (EBSD) technique is commonly used in texture analysis, but additional procedures are necessary to delimit the boundaries and assess the disorientation extent of each macrozone. Current methods frequently adopt c-axis misorientation criteria; however, this can sometimes cause a considerable spread of disorientation within a macrozone. Within this article, the development and application of a MATLAB-based computational tool for automatic macrozone identification from EBSD datasets is outlined, focusing on a more conservative approach that considers c-axis tilting and rotation. The tool assists in determining macrozones, contingent upon the disorientation angle and density-fraction. The clustering effectiveness, as depicted in pole-figure plots, is substantiated, and the influence of disorientation and fraction, the defining parameters of macrozone clustering, is elucidated. The tool achieved successful application to titanium forgings exhibiting both fully equiaxed and bimodal microstructures.

The phase-retrieval technique applied to propagation-based phase-contrast neutron imaging is demonstrated using a polychromatic beam. Imaging specimens with low absorption contrast and/or improving the signal-to-noise ratio, for example to facilitate, surgical site infection Time-dependent measurements, precisely tracked. A metal sample, fashioned to closely resemble a phase-pure object, and a bone sample characterized by partially D2O-filled canals, served as the demonstration samples for the technique. Following polychromatic neutron beam imaging, these samples underwent phase retrieval. Substantial signal-to-noise ratio improvements were achieved for each sample. In the bone sample, phase retrieval enabled the distinct separation of bone from D2O, a process necessary for the execution of in situ flow experiments. By employing deuteration contrast, neutron imaging circumvents the use of chemical contrast agents, emerging as a compelling complementary method to X-ray imaging of bone.

Two wafers from a single 4H-silicon carbide (4H-SiC) crystal, specifically one positioned near the crystal seed and the other positioned close to the cap, were examined by synchrotron white-beam X-ray topography (SWXRT), employing both back-reflection and transmission geometries to study dislocation generation and advancement during growth. A CCD camera system, first utilized in 00012 back-reflection geometry, enabled the initial recording of full wafer mappings, providing a comprehensive view of dislocation arrangements in terms of dislocation types, density, and a uniform distribution. The method, possessing comparable resolution to conventional SWXRT photographic film, allows for the identification of individual dislocations, including single threading screw dislocations, which are visible as white spots with diameters between 10 and 30 meters. Both analyzed wafers displayed a corresponding dislocation configuration, suggesting a consistent propagation of dislocations during the crystal growth period. High-resolution X-ray diffractometry reciprocal-space map (RSM) measurements, specifically in the symmetric 0004 reflection, enabled the systematic characterization of crystal lattice strain and tilt variations at selected wafer areas with distinct dislocation arrangements. RSM diffracted intensity distributions, resulting from diverse dislocation arrangements, demonstrated a clear connection with the prevalent dislocation type and density at specific local points.