A5084972748- 2D Materials and Applications
- Perovskite Materials and Applications
- Chalcogenide Semiconductor Thin Films
- Phase-change materials and chalcogenides
- Advanced Materials Characterization Techniques
- MXene and MAX Phase Materials
- Inorganic Chemistry and Materials
- Hydrogen embrittlement and corrosion behaviors in metals
- Quantum Dots Synthesis And Properties
- Graphene research and applications
- Topological Materials and Phenomena
- Radioactive element chemistry and processing
- Fusion materials and technologies
- Intermetallics and Advanced Alloy Properties
- Machine Learning in Materials Science
- Nuclear Materials and Properties
- Analytical chemistry methods development
- Photonic and Optical Devices
- Optical properties and cooling technologies in crystalline materials
- Semiconductor Quantum Structures and Devices
- Heusler alloys: electronic and magnetic properties
- Semiconductor materials and interfaces
- Advanced ceramic materials synthesis
- Ion-surface interactions and analysis
- High-Temperature Coating Behaviors
Matsys (United States)
2020-2021
Material Measurement Laboratory
2016-2020
National Institute of Standards and Technology
2016-2020
Paradigm (France)
2016
We introduce a simple criterion to identify two-dimensional (2D) materials based on the comparison between experimental lattice constants and mainly obtained from Materials-Project (MP) density functional theory (DFT) calculation repository. Specifically, if relative difference two for specific material is greater than or equal 5%, we predict them be good candidates 2D materials. have predicted at least 1356 such For all systems satisfying our criterion, manually create single layer...
We study the crystal symmetry of few-layer 1T' MoTe2 using polarization dependence second harmonic generation (SHG) and Raman scattering. Bulk is known to be inversion symmetric; however, we find that broken for finite crystals with even numbers layers, resulting in strong SHG comparable other transition-metal dichalcogenides. Group theory analysis signals allows definitive assignment all modes clears up a discrepancy literature. The results were also compared density functional simulations...
High volume manufacturing of devices based on transition metal dichalcogenide (TMD) ultra-thin films will require deposition techniques that are capable reproducible wafer-scale growth with monolayer control. To date, TMD efforts have largely relied upon sublimation and transport solid precursors minimal control over vapor phase flux gas-phase chemistry, which critical for scaling up laboratory processes to settings. address these issues, we report a new pulsed metalorganic chemical (MOCVD)...
The structural polymorphism in transition metal dichalcogenides (TMDs) provides exciting opportunities for developing advanced electronics. For example, MoTe2 crystallizes the 2H semiconducting phase at ambient temperature and pressure, but transitions into 1T' semimetallic high temperatures. Alloying with WTe2 reduces energy barrier between these two phases, while also allowing access to Td Weyl semimetal phase. WxTe2 alloy system is therefore promising change memory technology. However,...
Ultrathin transition metal dichalcogenides (TMDCs) have recently been extensively investigated to understand their electronic and optical properties. Here we study ultrathin Mo0.91W0.09Te2, a semiconducting alloy of MoTe2, using Raman, photoluminescence (PL), absorption spectroscopy. Mo0.91W0.09Te2 transitions from an indirect direct band gap in the limit monolayer thickness, exhibiting 1.10 eV, very close its MoTe2 counterpart. We apply tensile strain, for first time, tune structure these...
A facile, low-cost, scalable, catalyst-free solution-processed method is used to grow high-quality antimony selenide nanostructures from a molecular ink directly on flexible substrates for high-performance near-infrared photodetectors. The fabricated photodetectors exhibit fast response and high performance with excellent flexibility durability, suggesting strong potential broadband optoelectronic device applications.
Atom probe tomography (APT) can theoretically deliver accurate chemical and isotopic analyses at a high level of sensitivity, precision, spatial resolution. However, empirical APT data often contain significant biases that lead to erroneous concentration abundance measurements. The present study explores the accuracy quantitative performed via atom mass spectrometry. A machine learning-based adaptive peak fitting algorithm was developed provide reproducible mathematically defensible means...
We examine anharmonic contributions to the optical phonon modes in bulk Td-MoTe2 through temperature-dependent Raman spectroscopy. At temperatures ranging from 100 K 200 K, we find that all redshift linearly with temperature agreement Grüneisen model. However, below observe nonlinear frequency shifts some modes. demonstrate this behavior is consistent decay of an into multiple acoustic phonons. Furthermore, highest show large changes intensity and linewidth near T ≈ 250 correlate well Td→1T′...
Atom probe tomography (APT)-based isotopic analyses are becoming increasingly attractive for analysis applications requiring small volumes of material and sub-micrometer length scales, such as isotope geochemistry, nuclear safety, materials science. However, there is an open question within the atom community to reliability elemental analyses. Using our proposed guidelines, in conjunction with empirical calibration curve a machine learning-based adaptive peak fitting algorithm, we...
Surface modification is used to dramatically alter the thermal properties of a bulk metallic material. Thermal barrier coatings (TBCs) are typically applied using spray deposition or laser-based techniques create ceramic coating on metal substrate. In this study, an effective TBC created directly substrate by inducing surface chemical reactions. Aluminum–zirconium (Al–Zr) substrates induce surface-limited reactions that produce 75–80% decrease in conductivity and diffusivity, respectively....
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The structural polymorphism intrinsic to select transition metal dichalcogenides provides exciting opportunities for engineering novel devices. Of special interest are memory technologies that rely upon controlled changes in crystal phase, collectively known as phase change memories (PCMs). MoTe$_2$ is ideal PCMs the ground state energy difference between hexagonal (2H, semiconducting) and monoclinic (1T', metallic) phases minimal. This can be made arbitrarily small by substituting W Mo on...
Journal Article Towards Accurate and Reproducible Uranium Isotopic Analysis via Atom Probe Mass Spectrometry Get access Frederick Meisenkothen, Meisenkothen National Institute of Standards Technology, Gaithersburg, Maryland, United States Search for other works by this author on: Oxford Academic Google Scholar Mark McLean, McLean Irina Kalish, Kalish MATSYS, Inc., Sterling, Virginia, Daniel Samarov, Samarov Eric Steel Microscopy Microanalysis, Volume 26, Issue S2, 1 August 2020, Pages...
Molybdenum ditelluride (MoTe2), which can exist in a semiconducting prismatic hexagonal (2H) or metallic distorted octahedral (1T') phases, is one of the very few materials that exhibit metal-semiconductor transition. Temperature-driven 2H – 1T' phase transition bulk MoTe2 occurs at high temperatures (above ~900 C) and it usually accompanied by Te loss. The latter exacerbate control over reversibility Here, we study effects high-temperature annealing on single crystals. First, were grown...
We study the symmetry properties of 1T' MoTe2 using polarized Raman and second harmonic generation. find that while inversion is broken for even numbers layers, modes are nearly unchanged.