Questions In Materials Science Research Articles

Interaction graph engineering in trapped-ion quantum simulators with global drives

Trapped-ion quantum simulators have demonstrated a long history of studying the physics of interacting spin-lattice systems using globally addressed entangling operations. Yet despite the multitude of studies so far, most have been limited to studying variants of the same spin interaction model, namely an Ising model with power-law decay in the couplings. Here, we demonstrate that much broader classes of effective spin–spin interactions are achievable using exclusively global driving fields. Specifically, we find that these new categories of interaction graphs become achievable with perfect or near-perfect theoretical fidelity by tailoring the coupling of the driving fields to each vibrational mode of the ion crystal. Given the relation between the ion crystal vibrational modes and the accessible interaction graphs, we show how the accessible interaction graph set can be further expanded by shaping the trapping potential to include specific anharmonic terms. Finally, we derive a rigorous test to determine whether a desired interaction graph is accessible using only globally driven fields. These tools broaden the reach of trapped-ion quantum simulators so that they may more easily address open questions in materials science and quantum chemistry.

TEXplorer.org: Thermoelectric material properties data platform for experimental and first-principles calculation results

Scientific databases offer remarkable potential for solving complex questions in materials science, such as global optimization of materials and designing unknown materials for novel properties. ThermoElectric materials eXplorer (TEXplorer) is a web-based platform designed to collect and share all types of thermoelectric materials data, including synthesis information, materials characterization, transport measurements, and electronic structures obtained from experiments and computations. TEXplorer also provides valuable tools, such as an easy upload and download system, retrieval, automatic post-processing calculations, visualization of datasets, and toolkits for predicting thermoelectric properties through machine learning models. Using the platform, we collected and managed the thermoelectric dataset of SnSe and Bi2Te3 with various doping/alloying elements in this study in order to investigate the complex relationship between doping/alloying elements and the thermoelectric properties of host materials. The web-based interactive data platform enables efficient management and utilization of experimental and computational datasets, supporting the acceleration of data-driven materials research and autonomous material synthesis.

Machine-learned potentials for next-generation matter simulations.

The choice of simulation methods in computational materials science is driven by a fundamental trade-off: bridging large time- and length-scales with highly accurate simulations at an affordable computational cost. Venturing the investigation of complex phenomena on large scales requires fast yet accurate computational methods. We review the emerging field of machine-learned potentials, which promises to reach the accuracy of quantum mechanical computations at a substantially reduced computational cost. This Review will summarize the basic principles of the underlying machine learning methods, the data acquisition process and active learning procedures. We highlight multiple recent applications of machine-learned potentials in various fields, ranging from organic chemistry and biomolecules to inorganic crystal structure predictions and surface science. We furthermore discuss the developments required to promote a broader use of ML potentials, and the possibility of using them to help solve open questions in materials science and facilitate fully computational materials design.

4D-STEM of Beam-Sensitive Materials

ConspectusScanning electron nanobeam diffraction, or 4D-STEM (four-dimensional scanning transmission electron microscopy), is a flexible and powerful approach to elucidate structure from "soft" materials that are challenging to image in the transmission electron microscope because their structure is easily damaged by the electron beam. In a 4D-STEM experiment, a converged electron beam is scanned across the sample, and a pixelated camera records a diffraction pattern at each scan position. This four-dimensional data set can be mined for various analyses, producing maps of local crystal orientation, structural distortions, crystallinity, or different structural classes. Holding the sample at cryogenic temperatures minimizes diffusion of radicals and the resulting damage and disorder caused by the electron beam. The total fluence of incident electrons can easily be controlled during 4D-STEM experiments by careful use of the beam blanker, steering of the localized electron dose, and by minimizing the fluence in the convergent beam thus minimizing beam damage. This technique can be applied to both organic and inorganic materials that are known to be beam-sensitive; they can be highly crystalline, semicrystalline, mixed phase, or amorphous.One common example is the case for many organic materials that have a π-π stacking of polymer chains or rings on the order of 3.4-4.2 Å separation. If these chains or rings are aligned in some regions, they will produce distinct diffraction spots (as would other crystalline spacings in this range), though they may be weak or diffuse for disordered or weakly scattering materials. We can reconstruct the orientation of the π-π stacking, the degree of π-π stacking in the sample, and the domain size of the aligned regions. This Account summarizes illumination conditions and experimental parameters for 4D-STEM experiments with the goal of producing images of structural features for materials that are beam-sensitive. We will discuss experimental parameters including sample cooling, probe size and shape, fluence, and cameras. 4D-STEM has been applied to a variety of materials, not only as an advanced technique for model systems, but as a technique for the beginning microscopist to answer materials science questions. It is noteworthy that the experimental data acquisition does not require an aberration-corrected TEM but can be produced on a variety of instruments with the right attention to experimental parameters.

Opportunities for Cryogenic Electron Microscopy in Materials Science and Nanoscience.

Cryogenic electron microscopy (cryo-EM) was the basis for the 2017 Nobel Prize in Chemistry for its profound impact on the field of structural biology by freezing and stabilizing fragile biomolecules for near atomic-resolution imaging in their native states. Beyond life science, the development of cryo-EM for the physical sciences may offer access to previously inaccessible length scales for materials characterization in systems that would otherwise be too sensitive for high-resolution electron microscopy and spectroscopy. Weakly bonded and reactive materials that typically degrade under electron irradiation and environmental exposure can potentially be stabilized by cryo-EM, opening up exciting opportunities to address many central questions in materials science. New discoveries and fundamental breakthroughs in understanding are likely to follow. In this Perspective, we identify six major areas in materials science that may benefit from the interdisciplinary application of cryo-EM: (1) batteries, (2) soft polymers, (3) metal-organic frameworks, (4) perovskite solar cells, (5) electrocatalysts, and (6) quantum materials. We highlight long-standing questions in each of these areas that cryo-EM can potentially address, which would firmly establish the powerful tool's broad scope and utility beyond biology.

Atom Probe Tomography of Aluminium Alloys: A Systematic Meta-Analysis Review of 2018

Atom probe tomography (APT) is a microscopy technique that provides a unique combination of information, specifically the position and elemental identity of each atom in three dimensions. Although the mass and spatial resolution is not perfect, we are still able to gain insights into materials science questions that we cannot access using other techniques. This systematic meta-analysis review summarises research in 2018 that used APT to study materials science questions in aluminium alloys.

Low-energy band structure and even-odd layer number effect in AB-stacked multilayer graphene

How atoms acquire three-dimensional bulk character is one of the fundamental questions in materials science. Before addressing this question, how atomic layers become a bulk crystal might give a hint to the answer. While atomically thin films have been studied in a limited range of materials, a recent discovery showing how to mechanically exfoliate bulk crystals has opened up the field to study the atomic layers of various materials. Here, we show systematic variation in the band structure of high mobility graphene with one to seven layers by measuring the quantum oscillation of magnetoresistance. The Landau fan diagram showed distinct structures that reflected differences in the band structure, as if they were finger prints of multilayer graphene. In particular, an even-odd layer number effect was clearly observed, with the number of bands increasing by one for every two layers and a Dirac cone observed only for an odd number of layers. The electronic structure is significantly influenced by the potential energy arising from carrier screening associated with a gate electric field.

A review of predictive nonlinear theories for multiscale modeling of heterogeneous materials

Since the beginning of the industrial age, material performance and design have been in the midst of innovation of many disruptive technologies. Today's electronics, space, medical, transportation, and other industries are enriched by development, design and deployment of composite, heterogeneous and multifunctional materials. As a result, materials innovation is now considerably outpaced by other aspects from component design to product cycle. In this article, we review predictive nonlinear theories for multiscale modeling of heterogeneous materials. Deeper attention is given to multiscale modeling in space and to computational homogenization in addressing challenging materials science questions. Moreover, we discuss a state-of-the-art platform in predictive image-based, multiscale modeling with co-designed simulations and experiments that executes on the world's largest supercomputers. Such a modeling framework consists of experimental tools, computational methods, and digital data strategies. Once fully completed, this collaborative and interdisciplinary framework can be the basis of Virtual Materials Testing standards and aids in the development of new material formulations. Moreover, it will decrease the time to market of innovative products.

Application of maximum-entropy electrostatic potential in Materials Science.

Charge density (CD) studies by Maximum Entropy Method (MEM) (Sakata & Sato, 1990) from x-ray diffraction data have been widely applied to solve problems and questions in materials science during past two decades. Encapsulations of metal atoms (Takata et al, 1995), gas molecules, as well as protein molecules in the materials have been visualized as MEM CDs. The MEM CD technique is now regarded as a sophisticated technique for visualization in atomic scale. Electrostatic potential (EP) and electric field (EF) from x-ray diffraction data using MEM have been developed in 2006 (Tanaka et al, 2006). The EP & EF successfully applied to ferroelectric material PbTiO3 and a charge ordered manganite system. The method has huge potential in materials science since interaction in the non-atomic region can be visualized experimentally. One of the promising target for EP & EF analysis is host-guest systems, such as porous coordination polymers (PCPs), zeolites, clathrates as well as endohedral metallofullerenes[3]. In the case of host-guest systems, the guest atom(s) or molecule(s) are located in spatially wider sites in comparison to other type of materials. Therefore the detailed structural information in the spatially wider sites is one of the most important issues. In the present study, I present an application of MEM EP & EF analysis to host-guest related system, icosahedral B12 cluster materials and hydrogen adsorbed PCP. The EP studies clearly visualize doping sites in B12 based superconductor and adsorption sites in PCP. The EF enables us to estimate quantitative interaction from host to guest. The quantitative evaluation really bridges between experiment and theory in materials science.

Confocal Microscopy of Colloidal Suspensions

Colloidal systems or colloids consist of microparticles or nanoparticles (solute) uniformly suspended in a liquid (solvent), also called colloidal suspensions. They can mimic and exhibit microscopic or atomic aspects of molecular and atomic systems. They have been increasingly studied because of their similarity with atomic systems. They can be microscopically observed by optical microscopes because they are large enough in size and slow in motion to be monitored; microscopic methods are very useful and powerful in research on colloidal systems. Recently, confocal laser microscopy has been known as a powerful tool to obtain information of real-space and real-time behaviors of colloidal suspensions. In particular, it is possible to exactly track individual colloids in three dimensions with confocal microscopy. In this article, we briefly discuss the usefulness of confocal microscopy in colloidal systems that are currently used as model systems to resolve important questions in materials science.

Nanoscale Hard X-Ray Microscopy Methods for Materials Studies

This review discusses recent progress in the development of hard X-ray microscopy techniques for materials characterization at the nanoscale. Although the utility of traditionally ensemble-based X-ray techniques in materials research has been widely recognized, the utility of X-ray techniques as a tool for local characterization of nanoscale materials properties has undergone rapid development in recent years. Owing to a confluence of improvements in synchrotron source brightness, focusing optics fabrication, detection, and data analysis, nanoscale X-ray imaging techniques have moved beyond proof-of-principle experiments to play a central role in synchrotron user programs worldwide with high-impact applications made to materials science questions. Here, we review the current state of synchrotron-based, hard X-ray nanoscale microscopy techniques—including 3D tomographic visualization, spectroscopic elemental and chemical mapping, microdiffraction-based structural analysis, and coherent methods for nanomaterials imaging—with particular emphasis on applications to materials research.

Electron holography for fields in solids: Problems and progress

Electron holography initially was invented by Dennis Gabor for solving the problems raised by the aberrations of electron lenses in Transmission Electron Microscopy. Nowadays, after hardware correction of aberrations allows true atomic resolution of the structure, for comprehensive understanding of solids, determination of electric and magnetic nanofields is the most challenging task. Since fields are phase objects in the TEM, electron holography is the unrivaled method of choice. After more than 40 years of experimental realization and steady improvement, holography is increasingly contributing to these highly sophisticated and essential questions in materials science, as well to the understanding of electron waves and their interaction with matter.

Generalized biaxial shearing of MQMAS NMR spectra

Two dimensional multiple quantum (MQ) MAS NMR experiments have become popular due to the wide applicability of this technique to structural questions in materials science, the abundance of half-integer spin nuclei in the periodic table, and the ease of implementation on typical solid state NMR instruments. In spite of the high-resolution theoretically possible from such experiments, the homogeneous and inhomogeneous broadening factors inherent in many samples of interest can make spectral analysis challenging. We present several possible spectral shearing schemes that may be useful for spectral analysis, and in particular we introduce shearing in the directly detected dimension. We suggest that for amorphous or disordered samples that give broad spectral features, shearing may be used as a general tool for optimal positioning of these features relative to one another and for the characterization of isotropic chemical and quadrupolar shifts.

A Conversation with Prof. Chad Mirkin: Nanomaterials Architect

[Traditional chemists] had to take what was available to them, and then apply their really neat, new techniques to ask and to answer questions, whereas I could pick a system and make it and try to design what I thought was the perfect molecular system, or materials-based system, for asking and answering key questions in materials science.

Modern Developments in Multiphysics Materials Simulations

AbstractThe rapid advance of theoretical/numerical methods coupled with the gain in computational power has opened in the past few years a novel route to perform complex materials simulations, with hitherto not achievable accuracy and predictive power. Specifically the combination of atomistic and fully parameter‐free ab initio methods with concepts of mesoscopic/macroscopic approaches such as thermo‐dynamics, kinetics, statistical or continuum mechanics, has allowed researchers to take into account the hierarchical character of realistic materials. Recent results have proved extremely successful in many areas of metal physics, semiconductor technology, thin film growth, novel magnetic layers etc.To provide a forum for internationally leading top experts working in the field of multiscale modeling, and to discuss recent developments of multiscale/multiphysics simulations, an interdisciplinary “Symposium Modern Developments in Multiphysics Materials Simulations” (SYMS) was organized at the Spring 2008 Meeting of the German Physical Society (DPG) in Berlin. This meeting was a joint symposium of three sections within the DPG – “Surface Science”, “Metal Physics” and “Semiconductor Physics” and consisted of two parts: A symposium of invited speakers and a session with contributed talks and posters. In both sessions the wide range of materials science questions that can be nowadays addressed by multiscale approaches was impressively demonstrated.Topics presented at the meeting covered a range of as diverse topics, including hydrogen storage, catalysis, solidification processes, molecular systems, tailoring alloys, engineering materials, and materials synthesis.A number of these contributions are published in this issue of pss as regular articles. Similar to the meeting, the topics cover a wide range of recent developments and demonstrate the versatility of modern multiscale approaches in addressing complex materials science topics. They range from the application of neural networks to predict ground state crystalline phases, of combining DFT with kMC to study epitaxial growth of semiconductors, to the application of ab initio techniques with mechanical engineering concepts to jump scales directly from the atomistic to the macroscopic scale. As organizers we thank pss for providing a forum to present these papers. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Answering questions in materials science using FIB/SEM dual beam methods

Extended abstract of a paper presented at MC 2007, 33rd DGE Conference in Saarbrücken, Germany, September 2 – September 7, 2007

Critical questions in materials science and engineering for successful development of fusion power

It is the general conclusion of all national programs that the development of high-performance reduced-activation structural materials is essential for the successful development of fusion power. In this paper, the experience gleaned from previous programs to develop materials for high temperature structural applications is used to identify and discuss some of the most critical issues that must be addressed in the development of candidate materials for fusion structural applications. Critical issues discussed include radiation-induced solute segregation and implications on phase stability in the development of high-performance alloys/ceramics; the effects of very large amounts of helium on mechanical properties and the implications for alloy design/development; development of high temperature design methodology and incorporation of radiation effects into this methodology; the effects of radiation damage on flow localization, and the implications and approach to control the phenomena; and considerations of mass transfer and corrosion in complex fusion systems.

Intermolecular potentials--past, present, future.

When tackling the most fundamental of questions in materials science — what holds matter together — is the concept of an intermolecular potential still useful? Will it survive the emergence of more accurate and increasingly affordable ab initio calculations?

Incorporating Materials Science into an Undergraduate Applied Physics Curriculum

ABSTRACTThe Intermediate Physics laboratory is a pivotal course of the undergraduate physics curriculum. Besides its intrinsic importance for introducing modern physics experiments, this laboratory also plays an important role in addressing the needs of the future applied scientist and engineer using contemporary equipment for data acquisition and control. This laboratory course has a mix of standard (usually not directly addressing materials science questions) and newer experiments. Among the newer experiments, we have developed a kit for measuring the transverse and longitudinal Young and Shear modulus of a homemade concrete block by analyzing their standing modes of vibrations. The technique is similar to that of the C-215 American Society for Testing Materials (ASTM) Standard, but more appropriate for university educational setting, using ordinary student laboratory equipment and piezoelectric transducers. From these measurements, we also deduce Poisson's ratio. Students start measuring during the curing process of the concrete sample, something that it is not possible with the standard technique. However, our results have a precision comparable to that of the standard. Through the experiment, students learn about the properties of concrete. They make the samples following the C-192 ASTM standardized process, and review several concepts about waves such as wave equations, resonant modes of vibrations, dispersion relations, and standing modes.

Castaing’s Electron Microprobe and its Impact on Materials Science

A central theme of modern materials science has been the exploration of the relationship between the microstructure of a material and its macroscopic properties. Beginning in the late 19th century, the developing field of metallography permitted scientists to view the microstructure of metal alloys. Mechanical polishing followed by selective chemical etching produced differential relief on chemically distinct phases or at grain boundaries. With such specimens, reflection optical microscopy revealed structures with micrometer and even finer dimensions. The microstructural world that was found proved to be highly complex, and most alloys were observed to be chemically differentiated into two or more distinct phases. The answer to many materials science questions required knowledge of the specific composition of such fine scale phases. Castaing’s research was motivated by these considerations, as evidenced by the title of his first paper, “Application of electron probes to metallographic analysis”. The subsequent impact of Castaing’s electron probe microanalyzer (EPMA) has occurred across a broad range of the physical and biological sciences. Materials science has been one of the most active areas and chief beneficiaries, as well as a source of researchers who not only employed electron beam microanalysis to solve their problems but who also contributed innovations that advanced the microprobe field. For example, the abstracts of the First National Conference on Electron Probe Microanalysis contain numerous examples of advanced applications of the electron microprobe to materials science, including analysis of (1) refractory metal coatings (P. Lubllin and W. Sutkowski), (2) diffusion in the Ti-Nb system (D. Nagel and L. Birks), (3) Au-Al alloys (C. Nealey), (4) various steels (H. Nikkei), (5) Al-V-Mo-Ti alloys (R. Olsen), (6) corrosion of Ni-Co alloy (C. Spengler and R. Stickler), and (7) analysis of metal oxides and carbides (T. Ziebold). Integrated over 50 years, the impact of electron probe microanalysis on materials science has been so broad and varied, especially in its continued development and incorporation within scanning electron microscopy and analytical electron microscopy, that a suitably comprehensive review could consume the entire presentation time available for all topics to be covered in this conference! Instead, selected examples of critical applications will be presented to illustrate the impact in materials science.