Ferruginous beidellites with Al:Fe atomic ratios up to 2.36 were obtained when solutions containing Al, Fe2+ and H4SiO4 were adjusted to pH 8.5 with Ca(OH)2 and incubated at 95 °C in the presence of CaCO3 as a pH buffer. Incubation took place under cyclic reducing and oxidizing conditions achieved by adding 2 mM hydrazine at 14–15-d intervals over a period of 10–13 weeks. During the 14–15-d cycle, atmospheric oxygen slowly diffused through the high-density polyethylene bottles used, causing a slow oxidation of Fe(II) to Fe(III). The infrared (IR) spectra of the products approached that of natural beidellite, but indicated little change in octahedral Al:Fe ratio in the products for starting Al:Fe ratios from 2.5 up to 3.5, which was the highest Al:Fe ratio at which a well-crystallized product was obtained. Chemical analysis showed the presence of more Al+Fe in the products than could be incorporated into a dioctahedral formula. After the excess was assigned to a hydroxy-aluminium interlayer, the formula of the most Al-rich beidellite was calculated to be 0.575Ca(Si6.85A1.15)(Al2.47Fe1.53)O20(OH)4. This composition lay within the range recorded for the ferruginous beidellites that form in Vertisols.

X-ray diffraction of four natural samples of ferrihydrite indicates the presence of crystalline domains within the primary particles. The average diameter of the primary particles (determined from low-angle powder patterns) decreases from 4.1 nm to 2.5 nm as the domain size in the xy-plane (determined by applying the Scherrer equation to the broad [110] XRD peak at 0.26–0.27 nm) decreases from 1.0 nm to 0.77 nm. The Si content (measured by acid-oxalate extraction) increases from 4.1% to 6.1% as both the domain and particle sizes decrease; other factors, however, are likely to be important in influencing particle size. For one sample of ferrihydrite, the smallest possible domain (i.e., c = 0.94 nm in the z-direction) contains 36 O atoms and three Si atoms. A model for ferrihydrite is suggested in which silicate bonds to, and bridges, the surfaces of the domains. The model can account for several aspects of the behavior of siliceous ferrihydrites.

Three Ultic Haplorthods with significant illuviation of clay and spodic materials in the subalpine forests located in the Alishan area of central Taiwan were selected to identify the clay mineral compositions by X-ray diffraction (XRD) and to explain the transformation of the clay minerals. The three pedons are dominated by vermiculite and vermiculite-illite interstratified minerals, and they have minor kaolinite, quartz and gibbsite. No hydroxy interlayered vermiculite (HIV) was found in the E horizon of the three pedons because the forest soils are very acidic and have very low Al contents. The presence of HIV in the spodic (Bhs) and argillic horizons (Bt) of the three pedons was associated with greater free Fe and Al contents (Fed and Ald), more favorable pH ranges, and coatings of organo-metallic complexes which prevented continuous weathering. The specific pedogenic process, clay illuviation and podzolization occurred sequentially in the Alishan area, and induced the unusual clay mineral distribution and transformation. The largest amounts of illite are in the C horizon and the amounts of vermiculite increased with decreasing soil depths. A reverse distribution between illite and vermiculite through the soil profile was observed. Illite was transformed to vermiculite due to the strong weathering environment associated with extremely low exchangeable K contents. The weathering sequence of clay minerals of Spodosols with fine textures in the study area is proposed as: illite → vermiculite (or interstratified vermiculite-illite minerals) → HIV and vermiculite.

Calcium–magnesium–alumino-silicate (CMAS) particulates enter the aero-engine in a sandy environment, melt and infiltrate into 7 wt% yttria-stabilized zirconia (7YSZ) thermal barrier coatings (TBCs), reducing their lifetime. This leads to chemical degradation in 7YSZ accompanied by tetragonal to monoclinic phase transformation upon cooling. In this work, electron-beam physical vapor deposition coatings were infiltrated with a synthetic CMAS. Synchrotron X-ray diffraction measurements show that CMAS infiltration at 1250 °C has about 43% higher monoclinic phase volume fraction (PVF) at the coating surface compared to 1225 °C and remains consistently higher throughout the coating depth. Additionally, the increase in annealing time from 1 to 10 h results in a 31% higher monoclinic phase at the surface. Scanning electron microscopy revealed the presence of globular monoclinic phases corresponding spatially with the above findings. These results resolve the impact of time and temperature on CMAS infiltration kinetics which is important for mitigation.

This contribution reports on the biosynthesis of nickel oxide and zinc oxide nanoparticles (NiO-NPs & ZnO-NPs) via a natural extract from Moringa Oleifera leaves as an effective chelating and/or oxidizing/reduction agent of nickel nitrate hexahydrate and zinc nitrate hexahydrate. The structural and optical properties of these two types of semiconductors obtained in a similar procedure are investigated using X-rays Diffraction (XRD), Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR), diffuse reflectance UV-Visible-NIR and Photoluminescence (PL) techniques. The structural analysis shows the formation of pure cubic NiO-NPs and pure wurtzite ZnO-NPs with an average crystallite size of 17.80 nm and 10.81 nm respectively. Their band gaps, calculated from the diffuse reflectance analysis were found to be 4.28 eV and 3.35 eV respectively.

Iron aluminide intermetallic alloys are of great importance in many industries due to their excellent oxidation resistance, low cost, low density, resistance to corrosion and good ductility at room temperature. However, these alloys suffer limited room temperature ductility above 873 K. In this paper, a molecular dynamics-based LAMMPS-EAM was used to model Fe50-XMXAl doped systems with either Ag, Pt or Pd. The lattice side preferences of the dopant were deduced from their energy landscape, and Fe sub-lattices showed promising properties. It was found that the addition of Ag, Pt and Pd enhances the stability of Fe50-XMXAl composition. More importantly, Ag and Pd doped systems gave comparable transition temperatures to experimental findings of 1273 K and 1073 K, respectively. Their thermodynamic and the mechanical stability trends showed promising properties for industrial applications, displaying stability at a high temperature below 1300 K.

Bismuth telluride have regained significant attention as a prototype of topological insulator. Thin films of high quality have been investigated as a basic platform for novel spintronic devices. Low mobility of bismuth and high desorption coefficient of telluride compose a scenario where growth parameters have drastic effects on structural and electronic properties of the films. Recently [J. Phys. Chem. C 2019, 123, 24818−24825], a detailed investigation has been performed on the dynamics of defects in epitaxial films of this material, revealing the impact of film/substrate lattice misfit on the films’ lateral coherence. Very small lattice misfit (<0.05%) are expected to have no influence on quality of epitaxial system with atomic layers weakly bonded to each other by van der Waals forces, contrarily to what was observed. In this work, we investigate the correlation between lattice misfit and size and morphology of the film crystalline domains. Three-dimensional reciprocal-space maps of film Bragg reflections obtained with synchrotron X-rays are used to visualize the spatial conformation of the crystallographic domains through film thickness, while atomic force microscopy images provide direct information of the domains morphology at the film surface.

Melting, solidification and solid-state transformation of the intermetallic Ni3Sn compound were investigated in situ using synchrotron high-energy X-ray diffraction. It was observed that the compound undergoes a hexagonal to cubic transition before melting. In solidification, a disordered cubic phase crystallizes from the liquid at a large undercooling but it is reordered prior to bulk solidification. In melting and solidification, forced or natural flows are active bringing about significant changes of crystal orientations. These in situ observations provided insights into phase transformations of Ni3Sn at elevated temperatures and their roles in formation of metastable microstructure consisting of coarse grains and subgrains.

Investigations of the crystallization of aluminosilicate phases within Hanford nuclear waste glasses typically involve subjecting samples to the canister centerline cooling (CCC) schedule. This cooling schedule is representative of the slowest cooling thermal profile which these glasses will experience after the glass is poured into the high level waste (HLW) container. However, few investigations have observed how the crystallization behavior changes by varying the heat treatment schedule. In the present study, three Hanford HLW glasses are subjected to CCC and isothermal heat treatments (IHT) to better understand the evolution of phases and the chemical partitioning due to temperature schedule. Samples were characterized using electron probe microanalysis, X-ray diffraction, micro X-ray fluorescence, and micro X-ray absorption spectroscopy. From IHT, eucryptite and apatite phases were observed which were not observed during CCC. Spatially-resolved measurements demonstrated that the oxidation state of the iron was similar among glass and crystal, and we suggest a mechanism to describe the compositional fluctuations near the crystal-glass interface which influence crystallization.

We report a simple and feasible technique for the formation of well-distributed nickel nanodot arrays on both oxidized and unoxidized silicon substrate by a conventional annealing process. The shape and distribution of nickel nanodots were maintained by adjusting annealing temperature, time and the SiO2 buffer layer thickness in between nickel film and the silicon substrate. The diffusion of nickel into the silicon is significantly reduced when the nickel film on the oxidized silicon substrate is annealed at high temperature. From this conventional annealing technique, we achieve a maximum nickel nanodots density up to (7.94±1.92) nanodot counts/µm2 on the oxidized silicon substrate with a well-defined spherical shape by adjusting the thickness of nickel film as well as buffer SiO2 layer. In the next experiment, the surface charge distribution on the nickel nanodot arrays were characterized through the Kelvin probe force microscope (KPFM) on tapping mode. It is found that the nickel nanodots can store and release the electric charges under an applied bias voltage.

LiNi0.5Mn1.5O4 cathode material, which has a higher working voltage (4.7 v) than NCM and a moderate specific capacity (148 mAh/g theoretical), has been studied to understand the source of capacity fade during the first 100 cycles in a half cell. The work mainly consisted of high resolution TEM observations and analysis of the surface microstructural properties, before and after cycling. We found that the pristine material consisted almost entirely of large FCC spinal domains but with cycling appears small simple cubic spinel domains at the surface. It is proposed that these small changes of the surface microstructure leads to impedance rise that results in the premature arrival to the upper cutoff voltage of 4.85V during charging and the subsequent loss of capacity with cycling.

Control and manipulation of residual stresses in thin films is a key for attaining coatings with high mechanical and tribological performance. It is therefore imperative to have reliable residual stress measurements methods to further understand the dynamics involved. The sin2ψ method of X-ray diffraction was used to investigate the residual stresses on the tungsten carbide cobalt thin films deposited on a mild steel surface to understand the how the deposition parameters influence the generation of residual stresses within the substrate surface. X-ray spectra of the surface revealed an amorphous phase of the thin film therefore the stress measured was of the substrate surface and the effects of sputtering parameters on residual stress were analysed. Compressive stresses were identified within all samples studied. The results reveal that as the sputtering parameters are varied, the residual stresses also change. Optimum deposition parameters in terms of residual stresses were suggested.

P-type NiO powders with an average crystallite size of 16 nm as shown by x-ray diffraction analysis were produced via biosynthesis using cactus plant extract. SEM showed that the NiO powders consisted of particles with sizes in the 20-35 nm range. A cyclic voltammetric study of the NiO nanopowders showed a quasi-reversible redox processes with the NiO powder showing potential for pseudo capacitance. Through these findings the use of natural Cactus extracts is hereby shown to be a cost-effective and environmentally friendly alternative for preparing Nickel oxide nanosized powders that can be of use in a variety of energy storage applications.

In situ X-ray diffraction is one of the most useful tools for studying a variety of processes, among which crystallization of nanoparticles where phase purity and size control are desired. Growth kinetics of a single phase can be completely resolved by proper analysis of the diffraction peaks as a function of time. The peak width provides a parameter for monitoring the time evolution of the particle size distribution (PSD), while the peak area (integrated intensity) is directly related to the whole diffracting volume of crystallized material in the sample. However, to precisely describe the growth kinetics in terms of nucleation and coarsening, the correlation between PSD parameters and diffraction peak widths has to be established in each particular study. Corrections in integrated intensity values for physical phenomena such as variation in atomic thermal vibrations and dynamical diffraction effects have also to be considered in certain cases. In this work, a general correlation between PSD median value and diffraction peak width is deduced, and a systematic procedure to resolve time-dependent lognormal PSDs from in situ XRD experiments is described in details. A procedure to correct the integrated intensities for dynamical diffraction effects is proposed. As a practical demonstration, this analytical procedure has been applied to the single-phase crystallization process of bismuth ferrite nanoparticles.

Continued progress in artificial intelligence (AI) and associated demonstrations of superhuman performance have raised the expectation that AI can revolutionize scientific discovery in general and materials science specifically. We illustrate the success of machine learning (ML) algorithms in tasks ranging from machine vision to game playing and describe how existing algorithms can also be impactful in materials science, while noting key limitations for accelerating materials discovery. Issues of data scarcity and the combinatorial nature of materials spaces, which limit application of ML techniques in materials science, can be overcome by exploiting the rich scientific knowledge from physics and chemistry using additional AI techniques such as reasoning, planning, and knowledge representation. The integration of these techniques in materials-intelligent systems will enable AI governance of the scientific method and autonomous scientific discovery.

Functional and mechanical properties of modern devices are directly controlled by the stress and strain state acting on the materials within. For manufacturers, elastic strain engineering of complex materials systems throughout processing and utilization is crucial. This requires methodologies with ever-increasing spatial and temporal resolutions. On the other hand, the nanoscale elastic strain field around individual defects fundamentally controls the deformation of crystalline materials. To date, a variety of techniques are available for measuring elastic strain, including transmission electron microscopy, electron backscatter diffraction, and x-ray diffraction. Recent advances in instrumentation have dramatically improved speed and resolution, enabling direct elastic strain mapping during in situ deformation at the nanoscale. In addition, plastic strain can be determined during deformation using digital image correlation. Current techniques are surveyed here to accurately quantify complex strain fields at the nanoscale and their potential to resolve scientific challenges in materials science.

Increasing the number of quantum bits while preserving precise control of their quantum electronic properties is a significant challenge in materials design for the development of semiconductor quantum computing devices. Semiconductor heterostructures can host multiple quantum dots that are electrostatically defined by voltages applied to an array of metallic nanoelectrodes. The structural distortion of multiple-quantum-dot devices due to elastic stress associated with the electrodes has been difficult to predict because of the large micrometer-scale overall sizes of the devices, the complex spatial arrangement of the electrodes, and the sensitive dependence of the magnitude and spatial variation of the stress on processing conditions. Synchrotron X-ray nanobeam Bragg diffraction studies of a GaAs/AlGaAs heterostructure reveal the magnitude and nanoscale variation of these distortions. Investigations of individual linear electrodes reveal lattice tilts consistent with a 28-MPa compressive residual stress in the electrodes. The angular magnitude of the tilts varies by up to 20% over distances of less than 200 nm along the length of the electrodes, consistent with heterogeneity in the metal residual stress. A similar variation of the crystal tilt is observed in multiple-quantum-dot devices, due to a combination of the variation of the stress and the complex electrode arrangement. The heterogeneity in particular can lead to significant challenges in the scaling of multiple-quantum-dot devices due to differences between the charging energies of dots and uncertainty in the potential energy landscape. Alternatively, if incorporated in design, stress presents a new degree of freedom in device fabrication.

Silicon is a promising material for lithium-ion batteries. However, it expands by 300% on lithiation, leading to fracture. Nanostructuring of silicon is expected to be a promising method to improve the mechanical strength of the silicon electrodes. In the present work, a unique battery test cell was designed and fabricated to study the in situ stress evolution in the silicon nanowire (SiNW) electrode during electrochemical lithiation using synchrotron X-ray microdiffraction. The stress in the SiNWs at pristine state and during lithiation was evaluated using energy scans. The average stress in the pristine nanowires was found to be ∼40 MPa tensile, which changed to ∼325 MPa compressive on lithiation. Further, the deviatoric stress state in the SiNWs during lithiation was evaluated using Laue diffraction and the lithiated nanowires were found to be in triaxial stress state with high shear stresses. The technique and the findings provide new and more in-depth understanding of the stress evolution in the SiNWs during electrochemical lithiation.

Cerium oxide nanoparticles (CNPs) are of significant interest to the scientific community due to their widespread applications in a variety of fields. It is proposed that size-dependent variations in the extent of Ce3+ and Ce4+ oxidation states of cerium in CNPs determine the performance of CNPs in application environments. To obtain greater molecular and structural understanding of chemical state transformations previously reported for ceria of ≈3 nm nanoparticles (CNPs) in response to changing ambient conditions, micro-XRD and Raman measurements were carried out for various solution conditions. The particles were observed to undergo a reversible transformation from a defective ceria structure to a non-ceria amorphous oxyhydroxide/peroxide phase in response to the addition of 30% hydrogen peroxide. For CNPs made up of ∼8 nm crystallites, a partial transformation was observed, and no transformation was observed for CNPs made up of ∼40 nm crystallites. This observation of differences in size-dependent transition behavior may help explain the benefits of using smaller CNPs in applications requiring regenerative property.

The application of microwave radiation (MWR) during materials synthesis can generate a wide range of interesting phenomena, such as rapid, low-temperature phase transitions and the formation of nonequilibrium phases. However, the underlying mechanisms by which MWR can influence processes like nucleation, crystallization, sintering, and grain growth remain unknown. A critical need for studying these mechanisms is the ability to quantitatively characterize the effects of MWR exposure on atomic structure. In this regard, synchrotron X-ray sources provide an opportunity to shed new light on electromagnetic (EM) field–assisted synthesis due to the availability of high-energy X-rays that enable a wide range of experimental characterization techniques. Here, we review the use of synchrotron X-ray sources for both ex situ and in situ studies of MWR-assisted synthesis. While many synchrotron-based tools are available to characterize the structural effects of MWR from the micron down to the atomic scale, work in this field is ongoing, and no clear consensus exists regarding the underlying mechanisms of EM field–mediated phase transitions. We discuss the instrumentation available to study field–matter interaction mechanisms and identify future needs in synchrotron characterization to better understand how EM fields can engineer advanced materials.