Structural Information Of Materials Research Articles

Dynamic graph attention network-based crystal space-enriched representation for improving material property prediction

The machine learning approach applied to materials discovery is a popular research direction. Knowledge of quantum chemistry explains that the structure of a material determines its properties. Graph neural networks (GNNs) provide a unique way of predicting the macroscopic properties of molecules and crystals rather than by solving the computationally expensive Schrödinger equation. Graph neural networks can abundantly transform the structural information of materials into corresponding features, and many models based on graph neural networks have been applied to predict material properties. We developed a new model (DYCGNN) containing a node update module for our designed edge-graph attention network composition. Through the application of the edge-gatv2 module, this module can effectively learn the complex relationship between nodes and neighbouring nodes in the crystal. Based on the calculated weight coefficients of each neighbouring node, the representation of the node is updated more effectively. In addition, we fuse the position information of the nodes into the node eigenvectors to complement the spatial information of the crystal and enrich the complete representation of the crystal. As we investigate the DYCGNN model, we find that our approach can outperform the predictions of previous models and provide insights into material crystallization.

Development of a versatile electrochemical cell for in situ grazing-incidence X-ray diffraction during non-aqueous electrochemical nitrogen reduction.

In situ techniques are essential to understanding the behavior of electrocatalysts under operating conditions. When employed, in situ synchrotron grazing-incidence X-ray diffraction (GI-XRD) can provide time-resolved structural information of materials formed at the electrode surface. In situ cells, however, often require epoxy resins to secure electrodes, do not enable electrolyte flow, or exhibit limited chemical compatibility, hindering the study of non-aqueous electrochemical systems. Here, a versatile electrochemical cell for air-free in situ synchrotron GI-XRD during non-aqueous Li-mediated electrochemical N2 reduction (Li-N2R) has been designed. This cell not only fulfills the stringent material requirements necessary to study this system but is also readily extendable to other electrochemical systems. Under conditions relevant to non-aqueous Li-N2R, the formation of Li metal, LiOH and Li2O as well as a peak consistent with the α-phase of Li3N was observed, thus demonstrating the functionality of this cell toward developing a mechanistic understanding of complicated electrochemical systems.

A Multiscale Superpixel-Level Group Clustering Framework for Hyperspectral Band Selection

Hyperspectral imagery (HSI) contains hundreds of bands, which provide a wealth of spectral information and enable better characterization of features. However, the excessive dimensionality also poses a dimensional disaster for subsequent processing. Fortunately, band selection (BS) gives a straightforward and effective way to pick out a subset of bands with rich information and low correlation. Although many hyperspectral BS methods, especially clustering-based ones, have been proposed by researchers in recent years, the contextual information of adjacent bands and the spatial structural information of materials are not well investigated. Therefore, in this article, a multiscale superpixel-level group-clustering framework (MSGCF) has been proposed for hyperspectral BS. Different from previous, a new superpixel-level distance measure is elaborately utilized to group and cluster the spectral bands, which jointly considers the spectral context and spatial structure information. Concretely, to preserve the spatial structural information of HSI, multiple superpixel segmentation is first performed to generate superpixel maps in multiscales, which enables complementarity of multiple superpixel segmentation algorithms and adaptation to diverse scales of land cover types. Second, the grouping and clustering paradigm is introduced to conduct the contextual information among bands. Here the maximum points of superpixel-level KL- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\ell _{1}$ </tex-math></inline-formula> distance of adjacent bands are adopted as partition points to separate bands into groups, which encourages adjacent bands with strong correlation to be divided into the same group. Third, a superpixel-level fast density-based clustering method (SuFDPC) with superpixel-level <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\ell _{2, 1}$ </tex-math></inline-formula> distance is developed to select representative bands in every group. Finally, BS results are achieved with a ranking-based voting strategy by concerning information entropy and frequency of occurrence in a unified scheme. A series of ablation analyses and experimental comparisons on four real HSI datasets have been conducted, as well as similarity comparisons for the selected bands. The experimental results consistently demonstrated the effectiveness of our MSGCF approach. The codes of this work will be available at <uri xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">http://jiasen.tech/papers/</uri> for the sake of reproducibility.

Simultaneous two-color X-ray absorption spectroscopy using Laue crystals at an inverse-compton scattering X-ray facility.

X-ray absorption spectroscopy (XAS) is an element-selective technique that provides electronic and structural information of materials and reveals the essential mechanisms of the reactions involved. However, the technique is typically conducted at synchrotrons and usually only probes one element at a time. In this paper, a simultaneous two-color XAS setup at a laboratory-scale synchrotron facility is proposed based on inverse Compton scattering (ICS) at the Munich Compact Light Source (MuCLS), which is based on inverse Compton scattering (ICS). The setup utilizes two silicon crystals in a Laue geometry. A proof-of-principle experiment is presented where both silver (Ag) and palladium (Pd) K-edge X-ray absorption near-edge structure spectra were simultaneously measured. The simplicity of the setup facilitates its migration to other ICS facilities or maybe to other X-ray sources (e.g. a bending-magnet beamline). Such a setup has the potential to study reaction mechanisms and synergistic effects of chemical systems containing multiple elements of interest, such as a bimetallic catalyst system.

Simultaneous Reciprocal and Real Space X-Ray Imaging of Time-Evolving Systems

Imaging the (sub)micron scale over large areas with high temporal resolution becomes increasingly necessary for the development and investigation of novel materials under realistic operation conditions. Small angle x-ray scattering imaging methods provide micro- and nanoscale structural information of materials. A fundamental shortcoming of such methods is the long acquisition time required to investigate macroscopic objects. In this work, we propose a single shot imaging method that allows reciprocal space sensitivity at a local level while maintaining spatial resolution for imaging macroscopic objects. We use an instrument that is sensitive to the ultrasmall angle x-ray scattering range and utilize it to image unstable polydisperse particle systems. This allows us to observe in real time the evolution of the local average particle diameter due to the stratification of the microparticles.

Synthesis of WSe2 Nanorods by Selenium Powder Precursor for Photocatalytic Application and Fuel Additive

By reducing the size of semiconductor material up to nanoscale, the physical and chemical properties vary substantially, resulting in unique features due to their large surface area or the quantum size. Tungsten selenide (WSe2) nano semiconductor is synthesized by a solvothermal method using sodium tungstate and selenium powder as a precursor, PVP as a stabilizing agent, and urea as a precipitating agent. Structural information of material is elucidated by XRD, such as grain size and crystal orientation. Diffraction peaks are observed at 13.69°, 31.45°, 37.93°, 41.27°, 47.53°, 55.47°, 55.95° and 65.17° 2θ values which designate the (002), (100), (103), (006), (105), (110), (112) and (200), miller indices respectively. The XRD result shows that the structure of semiconducting nanoparticles is hexagonal in shape and purely crystalline. The SEM determined surface topography and morphology of material that particles are rod-like, and the average particle size of nanorods is 41 nm. By Fuel additive application, it is clear that WSe2 nano semiconductor dramatically affects the fuel’s properties and different parameters analyze its efficiency, i.e., fire and flash point, cloud and pour point, kinematic viscosity, specific gravity and calorific values. The previous research has shown that semiconducting nanoparticles are essential in degrading dyes from water. At nanoscale, WSe2 nano semiconductor has recently been developed as an efficient photocatalyst because of its attractive band gap estimated as 1.8609 eV. WSe2 is an excellent catalyst because that Kapp values increase linearly from 0.0023 to 0.0037 min−1 with increase in catalyst dose from 0.01 to 0.05 g. In addition, it behaves as a good additive because the calorific value increased from 10,263 to 31,930 Jg−1 by the increase in additive dose from 20 to 80 ppm.

Electron transport behavior of polymer‐derived amorphous silicoboron carbonitrides

AbstractElectron transport behavior of polymer‐derived amorphous silicoboron carbonitride (a‐SiBCNs) ceramics was studied by measuring DC/AC conductivities and optical absorption as functions of the temperature. Structural information of materials was investigated by combining X‐ray diffraction (XRD), nuclear magnetic resonance (NMR), X‐ray photoelectron spectroscopy (XPS), Raman spectroscopy, and electron paramagnetic resonance (EPR) techniques. Conductive mechanisms and electronic structure of the materials (eg, hopping mechanism, conduction band, band‐tail, and defect energy) were deduced by fitting experimental results to theoretical models. Results revealed that DC/AC conduction of materials followed band‐tail hopping mechanism instead of previously assumed variable‐range hopping mechanism. Hopping mechanism, associated with overlapped band‐tail and defect levels, was likely originated by the presence of certain number of defects and highly disordered structure of materials. The content of donor defects in materials was considered to have great influence on the type of electronic mechanism. These results were discussed in line with microstructural evolution of materials.

Stereo-vision three-dimensional reconstruction of curvilinear structures imaged with a TEM

Deriving accurate three-dimensional (3-D) structural information of materials at the nanometre level is often crucial for understanding their properties. Tomography in transmission electron microscopy (TEM) is a powerful technique that provides such information. It is however demanding and sometimes inapplicable, as it requires the acquisition of multiple images within a large tilt arc and hence prolonged exposure to electrons. In some cases, prior knowledge about the structure can tremendously simplify the 3-D reconstruction if incorporated adequately. Here, a novel algorithm is presented that is able to produce a full 3-D reconstruction of curvilinear structures from stereo pair of TEM images acquired within a small tilt range that spans from only a few to tens of degrees. Reliability of the algorithm is demonstrated through reconstruction of a model 3-D object from its simulated projections, and is compared with that of conventional tomography. This method is experimentally demonstrated for the 3-D visualization of dislocation arrangements in a deformed metallic micro-pillar.

Electron ptychographic microscopy for three-dimensional imaging

Knowing the three-dimensional structural information of materials at the nanometer scale is essential to understanding complex material properties. Electron tomography retrieves three-dimensional structural information using a tilt series of two-dimensional images. In this paper, we report an alternative combination of electron ptychography with the inverse multislice method. We demonstrate depth sectioning of a nanostructured material into slices with 0.34 nm lateral resolution and with a corresponding depth resolution of about 24–30 nm. This three-dimensional imaging method has potential applications for the three-dimensional structure determination of a range of objects, ranging from inorganic nanostructures to biological macromolecules.

New insights in weathering analysis of anhydrous cements by using high spectral and spatial resolution Confocal Raman Microscopy

Raman spectroscopy combined with Confocal microscopy is a non-destructive technique that provides relevant structural information in materials. In this study, we present non-destructive Raman image and structural analysis of anhydrous cements with carbonation evidences by means of Confocal Raman Microscopy (CRM). The results obtained by CRM have been contrasted with the techniques commonly used for this purpose as FTIR and DTA/TG. CRM shows the main cement phases distribution (C2S and C3S) reveals their degree of weathering. The results obtained by CRM evidence a surprising coexistence of carbonate with amorphous carbon indicating that weathering mechanism in more complex than expected. Moreover, the size of sulphate particles contributes kinetically to weathering reaction. The weathering of cement particles by the atmospheric agents requires thus the combined action of amorphous carbon and sulphate. This study opens new analytical possibilities applied to commercial cements due to the combined chemical and spatial high resolution of CRM.Cement chemistry notation: C: CaO, S: SiO2, H: H2O, A: Al2O3, F: Fe2O3, $: SO3.

Solid-state NMR and short-range order in crystalline oxides and silicates: a new tool in paramagnetic resonances.

Most applications of high-resolution NMR to questions of short-range order/disorder in inorganic materials have been made in systems where ions with unpaired electron spins are of negligible concentration, with structural information extracted primarily from chemical shifts, quadrupolar coupling parameters, and nuclear dipolar couplings. In some cases, however, the often-large additional resonance shifts caused by interactions between unpaired electron and nuclear spins can provide unique new structural information in materials with contents of paramagnetic cations ranging from hundreds of ppm to several per cent and even higher. In this brief review we focus on recent work on silicate, phosphate, and oxide materials with relatively low concentrations of paramagnetic ions, where spectral resolution can remain high enough to distinguish interactions between NMR-observed nuclides and one or more magnetic neighbors in different bonding configurations in the first, second, and even farther cation shells. We illustrate the types of information available, some of the limitations of this approach, and the great prospects for future experimental and theoretical work in this field. We give examples for the effects of paramagnetic transition metal, lanthanide, and actinide cation substitutions in simple oxides, pyrochlore, zircon, monazite, olivine, garnet, pyrochlores, and olivine structures.

Development and tests of a new prototype detector for the XAFS beamline at Elettra Synchrotron in Trieste

The XAFS beamline at Elettra Synchrotron in Trieste combines X-ray absorption spectroscopy and X-ray diffraction to provide chemically specific structural information of materials. It operates in the energy range 2.4-27 keV by using a silicon double reflection Bragg monochromator. The fluorescence measurement is performed in place of the absorption spectroscopy when the sample transparency is too low for transmission measurements or the element to study is too diluted in the sample. We report on the development and on the preliminary tests of a new prototype detector based on Silicon Drift Detectors technology and the SIRIO ultra low noise front-end ASIC. The new system will be able to reduce drastically the time needed to perform fluorescence measurements, while keeping a short dead time and maintaining an adequate energy resolution to perform spectroscopy. The custom-made silicon sensor and the electronics are designed specifically for the beamline requirements.

Raman spectroscopy explores molecular structural signatures of hidden materials in depth: Universal Multiple Angle Raman Spectroscopy.

Non-invasive 3D imaging in materials and medical research involves methodologies such as X-ray imaging, MRI, fluorescence and optical coherence tomography, NIR absorption imaging, etc., providing global morphological/density/absorption changes of the hidden components. However, molecular information of such buried materials has been elusive. In this article we demonstrate observation of molecular structural information of materials hidden/buried in depth using Raman scattering. Typically, Raman spectroscopic observations are made at fixed collection angles, such as, 90°, 135°, and 180°, except in spatially offset Raman scattering (SORS) (only back scattering based collection of photons) and transmission techniques. Such specific collection angles restrict the observations of Raman signals either from or near the surface of the materials. Universal Multiple Angle Raman Spectroscopy (UMARS) presented here employs the principle of (a) penetration depth of photons and then diffuse propagation through non-absorbing media by multiple scattering and (b) detection of signals from all the observable angles.

High-Energy Synchrotron X-Ray Diffraction and Its Application to In Situ Structural Phase-Transition Studies in Complex Sample Environments

A solid may undergo a phase transition due to internal interaction competition or external stimuli. It is increasingly recognized that the lattice degrees of freedom often play a crucial role, especially in the vicinity of competing phases, where many intriguing properties exist. A crystal structure transition is usually accompanied by a drastic change in the mechanical, electrical, magnetic, and other properties. In situ study of the microscopic structural information of materials during phase transformation is of ultimate importance not only in understanding fundamental mechanisms but also in developing and processing advanced materials for broad technological applications. The availability of synchrotron-generated high-flux and high-energy x-rays has significantly advanced the field of materials research because of the deep penetration and low absorption of high-energy x-rays. Synchrotron high-energy x-ray diffraction facilities provide great research opportunities, especially for probing structural phase transformations of bulk materials in real time and in realistic conditions. In this overview we present technical details and capabilities of a synchrotron high-energy x-ray facility and its applications to in situ structural investigations of phase transitions in advanced materials in research areas ranging from condensed-matter and materials science and engineering to energy science.

Invention of Materials and Structural Observation

Neutron scattering techniques have been recognized to get structural information of materials. In this writing I show briefly that structural information can play an important role to get seeds for invention of new materials through recent works of the hydrogen absorbing nano-graphite. Especially, pulsed sources and the consequent time-of-flight diffraction and spectroscopy techniques provide special features advantageous for investigating nano-and complex materials. Therefore, material scientists can anticipate that J-PARC will give them the various kinds of structural properties of complex materials for planning new materials for human life.

Ab initio structure determination via powder X-ray diffraction

Structure determination by powder X-ray diffraction data has gone through a recent surge since it has become important to get to the structural information of materials which do not yield good quality single crystals. Although the method of structure completion when once the starting model is provided is facile through the Rietveld refinement technique, the structure solutionab initio is still not push-button technology. In this article a survey of the recent development in this area is provided with an illustration of the structure determination of α-NaBi3V2O10.

Summary and conclusions of a program addressing aging of nuclear power plant concrete structures

Research has been conducted by the Oak Ridge National Laboratory to address aging management of nuclear power plant concrete structures. The purpose was to identify potential structural safety issues and acceptance criteria for use in continued service assessments. The focus of this program was on structural integrity rather than on leaktightness or pressure retention of concrete structures. Primary program accomplishments include formulation of a Structural Materials Information Center that contains data and information on the time variation of material properties under the influence of pertinent environmental stressors and aging factors for 144 materials, an aging assessment methodology to identify critical structures and degradation factors that can potentially impact their performance, guidelines and evaluation criteria for use in condition assessments of reinforced concrete structures, and a reliability-based methodology for current condition assessments and estimations of future performance of reinforced concrete nuclear power plant structures. In addition, in-depth evaluations were conducted of several nondestructive evaluation and repair-related technologies to develop guidance on their applicability.

Aging management of containment structures in nuclear power plants

Research is being conducted by Oak Ridge National Laboratory under US Nuclear Regulatory commission (USNRC) sponsorship to address aging management of nuclear power plant containment and other safety-related structures. Documentation is being prepared to provide the USNRC with potential structural safety issues and acceptance criteria for use in continued service evaluations of nuclear power plants. Accomplishments include development of a Structural Materials Information Center containing data and information on the time variation of 144 material properties under the influence of pertinent environmental stressors or aging factors, evaluation of models for potential concrete containment degradation factors, development of a procedure to identify critical structures and degradation factors important to aging management, evaluations of non-destructive evaluation techniques, assessments of European and North American repair practices for concrete, review of parameters affecting corrosion of metals embedded in concrete, and development of methodologies for making current condition assessments and service life predictions of new or existing reinforced concrete structures in nuclear power plants.

Research and development at the structural materials information center

The U.S. Nuclear Regulatory Commission has initiated a Structural Aging Program at the Oak Ridge National Laboratory to identify potential structural safety issues related to continued service of nuclear power plants and to establish criteria for evaluating and resolving these issues. One of the tasks in this program focuses on the establishment of a Structural Materials Information Center where long-term and environment-dependent properties of concretes and other structural materials are being collected and assembled into a data base. These properties will be used to evaluate the current condition of critical structural components in nuclear power plants and to estimate their future performance during the continued service period.