A eutectoid phase transformation was exhibited by the perovskite CeCrO when heated in air. The kinetics of the reaction, microstructure of the product, and mechanisms of the transformation were studied using thermogravimetric analysis, X-ray and Raman spectroscopy, X-ray diffraction, and electron microscopy. Fluorite CeO and corundum CrO were formed from the decomposition of CeCrO.
View Article and Find Full Text PDFACS Appl Mater Interfaces
October 2024
Neodymium tritelluride is a layered van der Waals material, with correlated electronic properties including high electronic mobility, charge density waves, and antiferromagnetism. We developed a solution synthesis method to form free-standing nanosheets of NdTe, with nanosheet lateral dimensions of 200-400 nm. The morphology of the nanosheet was influenced by the neodymium precursor.
View Article and Find Full Text PDFChemical vapour deposition (CVD) synthesis of graphene on copper has been broadly adopted since the first demonstration of this process. However, widespread use of CVD-grown graphene for basic science and applications has been hindered by challenges with reproducibility and quality. Here we identify trace oxygen as a key factor determining the growth trajectory and quality for graphene grown by low-pressure CVD.
View Article and Find Full Text PDFTemperature is a fundamental physical quantity important to the physical and biological sciences. Measurement of temperature within an optically inaccessible three-dimensional (3D) volume at microscale resolution is currently limited. Thermal magnetic particle imaging (T-MPI), a temperature variant of magnetic particle imaging (MPI), hopes to solve this deficiency.
View Article and Find Full Text PDFComputer vision techniques have immense potential for materials design applications. In this work, we introduce an integrated and general-purpose AtomVision library that can be used to generate and curate microscopy image (such as scanning tunneling microscopy and scanning transmission electron microscopy) data sets and apply a variety of machine learning techniques. To demonstrate the applicability of this library, we (1) establish an atomistic image data set of about 10 000 materials with large structural and chemical diversity, (2) develop and compare convolutional and atomistic line graph neural network models to classify the Bravais lattices, (3) demonstrate the application of fully convolutional neural networks using U-Net architecture to pixelwise classify atom versus background, (4) use a generative adversarial network for super resolution, (5) curate an image data set on the basis of natural language processing using an open-access arXiv data set, and (6) integrate the computational framework with experimental microscopy images for Rh, FeO, and SnS systems.
View Article and Find Full Text PDFThe structural, thermal, and electronic properties of BaMnSe were investigated. Analysis of the low-temperature heat capacity revealed a low Debye temperature and a low average speed of sound that, together with the bonding in this material, result in a low thermal conductivity over a relatively large temperature range. Density functional theory and calculated electron localization were employed to investigate the electronic structure and bonding.
View Article and Find Full Text PDFHigh-throughput density functional theory (DFT) calculations allow for a systematic search for conventional superconductors. With the recent interest in two-dimensional (2D) superconductors, we used a high-throughput workflow to screen over 1000 2D materials in the JARVIS-DFT database and performed electron-phonon coupling calculations, using the McMillan-Allen-Dynes formula to calculate the superconducting transition temperature () for 165 of them. Of these 165 materials, we identify 34 dynamically stable structures with transition temperatures above 5 K, including materials such as WN, NbO, ZrBrO, TiClO, NaSnS, MgBC, and the previously unreported MgBN ( = 21.
View Article and Find Full Text PDFCharacterization of the magnetization dynamics of single-domain magnetic nanoparticles (MNPs) is important for magnetic particle imaging (MPI), magnetic resonance imaging (MRI), and emerging medical diagnostic/therapeutic technologies. Depending on particle size and temperature, nanoparticle magnetization relaxation time constants span from nanoseconds to seconds. In solution, relaxation occurs via coupled Brownian and Néel relaxation mechanisms.
View Article and Find Full Text PDFThe recent introduction of slow vacuum filtration (SVF) technology has shown great promise for reproducibly creating high-quality, large-area aligned films of single-wall carbon nanotubes (SWCNTs) from solution-based dispersions. Despite clear advantages over other SWCNT alignment techniques, SVF remains in the developmental stages due to a lack of an agreed-upon alignment mechanism, a hurdle which hinders SVF optimization. In this work, the filter membrane surface is modified to show how the resulting SWCNT nematic order can be significantly enhanced.
View Article and Find Full Text PDFIn targeting reduced valent lanthanide chalcogenides, we report the first nanoparticle synthesis of the mixed-valent ferromagnets Eu S and EuSm S . Using divalent lanthanide halides with bis(trimethylsilyl)sulfide and oleylamine, we prepared nanoparticles of EuS, Eu S , EuSm S , SmS , and Sm S . All nanoparticle phases were identified using powder X-ray diffraction, transmission electron microscopy was used to confirm morphology and nanoparticle size, and magnetic susceptibility measurements for determining the ordering temperatures and valence.
View Article and Find Full Text PDFMany technological applications depend on the response of materials to electric fields, but available databases of such responses are limited. Here, we explore the infrared, piezoelectric and dielectric properties of inorganic materials by combining high-throughput density functional perturbation theory and machine learning approaches. We compute Γ-point phonons, infrared intensities, Born-effective charges, piezoelectric, and dielectric tensors for 5015 non-metallic materials in the JARVIS-DFT database.
View Article and Find Full Text PDFOver the past decade, substantial progress has been made in the chemical control (chiral enrichment, length sorting, handedness selectivity, and filling substance) of single-wall carbon nanotubes (SWCNTs). Recently, it was shown that large, horizontally aligned films can be created out of postprocessed SWCNT solutions. Here, we use machine-vision automation and parallelization to simultaneously produce globally aligned SWCNT films using pressure-driven filtration.
View Article and Find Full Text PDFColloidal-based solution syntheses offer a scalable and cost-efficient means of producing 2D nanomaterials in high yield. While much progress has been made toward the controlled and tailorable synthesis of semiconductor nanocrystals in solution, it remains a substantial challenge to fully characterize the products' inherent electronic transport properties. This is often due to their irregular morphology or small dimensions, which demand the formation of colloidal assemblies or films as a prerequisite to performing electrical measurements.
View Article and Find Full Text PDFTin(ii) monosulfide (SnS) is a layered, anisotropic material that is of interest as a two-dimensional semiconductor for opto-electronic, thermoelectric, and piezoelectric applications. In this study, the effect of work function on contact behavior was investigated. Ni/Au, Pd/Au, Cr/Au, and Ti/Au contacts were fabricated onto individual, solution-synthesized, p-type SnS nanoribbons.
View Article and Find Full Text PDFThe shapes of noble metal nanoparticles directly impact their properties and applications, including in catalysis and plasmonics, and it is therefore important to understand how multiple distinct morphologies can be controllably synthesized. Solution routes offer powerful capabilities for shape-controlled nanoparticle synthesis, but the earliest stages of the reaction are difficult to interrogate experimentally and much remains unknown about how metal nanoparticle morphologies emerge and evolve. Here, we use a well-established polyol process to synthesize uniform rhodium nanoparticle cubes, icosahedra, and triangular plates using bromide, trifluoroacetate, and chloride ligands, respectively.
View Article and Find Full Text PDFNanostructured transition-metal phosphides have recently emerged as Earth-abundant alternatives to platinum for catalyzing the hydrogen-evolution reaction (HER), which is central to several clean energy technologies because it produces molecular hydrogen through the electrochemical reduction of water. Iron-based catalysts are very attractive targets because iron is the most abundant and least expensive transition metal. We report herein that iron phosphide (FeP), synthesized as nanoparticles having a uniform, hollow morphology, exhibits among the highest HER activities reported to date in both acidic and neutral-pH aqueous solutions.
View Article and Find Full Text PDFColloidal hybrid nanoparticles are an important class of materials that incorporate multiple nanoparticles into a single system through solid-state interfaces, which can result in multifunctionality and the emergence of synergistic properties not found in the individual components. These hybrid structures are typically produced using seeded-growth methods, where preformed nanoparticles serve as seeds onto which additional domains are added through subsequent reactions. For hybrid nanoparticles that contain more than two domains, multiple configurations with distinct connectivities and functionalities are possible, and these can be considered as nanoparticle analogues of molecular isomers.
View Article and Find Full Text PDFNanoparticles of nickel phosphide (Ni2P) have been investigated for electrocatalytic activity and stability for the hydrogen evolution reaction (HER) in acidic solutions, under which proton exchange membrane-based electrolysis is operational. The catalytically active Ni2P nanoparticles were hollow and faceted to expose a high density of the Ni2P(001) surface, which has previously been predicted based on theory to be an active HER catalyst. The Ni2P nanoparticles had among the highest HER activity of any non-noble metal electrocatalyst reported to date, producing H2(g) with nearly quantitative faradaic yield, while also affording stability in aqueous acidic media.
View Article and Find Full Text PDFThe polyol process is one of the most common methods for synthesizing metal nanoparticles with controlled shapes and sizes due to its wide applicability and ease of use. These nanostructures often have unique morphology-dependent properties that are useful in a range of applications, including catalysis, plasmonics, and medical diagnostics and therapeutics. While many variations of the polyol process have been developed to produce shape-controlled nanoparticles, there has been no systematic investigation that defines the influence of the solvent on the shape and uniformity of the product.
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