A5032340088- Diamond and Carbon-based Materials Research
- Energetic Materials and Combustion
- High-pressure geophysics and materials
- Electrochemical Analysis and Applications
- Ionic liquids properties and applications
- Corrosion Behavior and Inhibition
- Additive Manufacturing Materials and Processes
- Ion-surface interactions and analysis
- Electron and X-Ray Spectroscopy Techniques
- Fuel Cells and Related Materials
- Electrodeposition and Electroless Coatings
- Anodic Oxide Films and Nanostructures
- Boron and Carbon Nanomaterials Research
- Nuclear Physics and Applications
- Nuclear Materials and Properties
- Metal and Thin Film Mechanics
- Electrocatalysts for Energy Conversion
- Additive Manufacturing and 3D Printing Technologies
- Aluminum Alloys Composites Properties
- Laser Material Processing Techniques
- Combustion and Detonation Processes
- Electronic and Structural Properties of Oxides
- Hydrogen embrittlement and corrosion behaviors in metals
- Aerogels and thermal insulation
- Fusion materials and technologies
Lawrence Livermore National Laboratory
2017-2025
General Atomics (United States)
2021-2022
Argonne National Laboratory
2013-2021
Lawrence Livermore National Security
2017-2020
SUNY Polytechnic Institute
2019
University of Birmingham
2010-2013
Vrije Universiteit Brussel
2013
Texas Tech University
2007
Circumventing spatter Laser powder bed fusion is an additive manufacturing technique that laser-melts layer by to build a three-dimensional (3D) part. Khairallah et al. used experiments and multiphysics model determine the origin of melt defect formation degrade properties built parts (see Perspective Polonsky Pollock). Informed modulation laser power important avoid disturbing creating shadowing. This reduces pore formations leads more uniform 3D-printed parts. Science , this issue p. 660 ;...
A new class of castable cerium strengthened aluminum alloys has phenomenal high temperature properties without the need for heat treatment.
Advanced in situ characterization is essential for determining the underlying dynamics of laser-material interactions central to both laser welding and rapidly expanding field additive manufacturing. Traditional techniques leave a critical experimental gap understanding complex subsurface fluid flow metal evaporation inherent laser-induced heating metal. Herein, ultra-high-speed transmission X-ray imaging revealed be bridging this information gap, particularly via comparison with validation...
The early stages of nanocrystal nucleation and growth are still an active field research remain unrevealed. In this work, by the combination aberration-corrected transmission electron microscopy (TEM) electrochemical characterization electrodeposition different metals, we provide a complete reformulation Volmer-Weber 3D island mechanism, which has always been accepted to explain metal thin-film on low-energy substrates. We have developed Generalized Electrochemical Aggregative Growth...
Supported nanoparticle synthesis and assembly have application in a wide range of modern day applications. Key to the manipulation particle is an understanding interaction between particles solvent. Here, we employ comprehensive situ approach, together with ex SEM imaging, study supported palladium nanoparticles, electrodeposited from 2:1 urea:choline Cl– DES. Using cyclic voltammetry, confirm expected adsorption electroactive species onto deposited particles. On basis our experimental...
Abstract Transit through the carbon liquid phase has significant consequences for subsequent formation of solid nanocarbon detonation products. We report dynamic measurements condensation and solidification into nano-onions over ∽200 ns by analysis time-resolved, small-angle X-ray scattering data acquired during a hydrogen-free explosive, DNTF (3,4-bis(3-nitrofurazan-4-yl)furoxan). Further, thermochemical modeling predicts direct to graphite transition products ~200 post-detonation. Solid...
Decreasing microstructural length scales to the nanoscale is a proven way of increasing strength, but intrinsic metastability such structures typically makes them susceptible thermally activated coarsening. Recent advances in additive manufacturing permit bulk-nanostructured materials be produced through rapid solidification, like other metastable as-built coarsen rapidly with even modest thermal exposure. Here, selective laser melting employed produce an Al-Ce-based alloy high mechanical...
By using an optimized characterization approach that combines aberration-corrected transmission electron microscopy, tomography, and in situ ultrasmall angle X-ray scattering (USAXS), we show the early stages of Pt electrochemical growth on carbon substrates may be affected by aggregation, self-alignment, partial coalescence nanoclusters d ≈ 2 nm. The morphology resulting nanostructures depends degree recrystallization nanocluster aggregates, which turn electrodeposition potential. At low...
Abstract Biological membranes provide a fascinating example of separation system that is multifunctional, tunable, precise, and efficient. Biomimetic membranes, which mimic the architecture cellular have potential to deliver significant improvements in specificity permeability. Here, fully synthetic biomimetic membrane reported incorporates ultra‐efficient 1.5 nm diameter carbon nanotube porin (CNTPs) channels block‐copolymer matrix. It demonstrated CNTPs maintain high proton water...
Laser powder bed fusion (LPBF) additive manufacturing and laser welding are powerful metal processing techniques with broad applications in advanced sectors such as the biomedical aerospace industries. One common process variable that can tune laser-material interaction dynamics these two is adjustment of composition pressure atmosphere which conducted. While some physical mechanisms governed by ambient well known from literature, it remains unclear how extend to distinct conditions LPBF. In...
Detonation nanodiamond (DND) is known to form aggregates that significantly reduce their unique nanoscale properties and require postprocessing separate. How when DND an important question has not been answered experimentally could provide the foundation for approaches limit aggregation. To answer this question, time-resolved small-angle X-ray scattering was performed during detonation of high-explosives are expected condense particulates in diamond, graphite, liquid regions carbon phase...
Two-dimensional (2D) materials have attracted intense interest due to their potential for applications in fields ranging from chemical sensing catalysis, energy storage, and biomedicine. Recently, peptoids, a class of biomimetic sequence-defined polymers, been found self-assemble into 2D crystalline sheets that exhibit unusual properties, such as high stability the ability self-repair. The structure peptoid is close peptide except side chains are appended amide nitrogen rather than α carbon....
Anion exchange membranes (AEMs) offer a cost-effective alternative to proton as alkaline fuel cells and electrolyzers permit the use of non-platinum group electrodes components. Despite continued progress, operational lifetime stability these limit widespread adoption AEM-based electrochemical technologies. This study presents flexible easily implemented ultraviolet (UV)-initiated nitrene-based cross-linking method which uses small, facile organic azide precursor. As proof concept, we...
Hydrogel infused additive manufacturing (HIAM) is an emerging technique for the of ceramics and metals. Distinct from slurry- or powder-based techniques, a hydrogel scaffold obtained in the...
Characterization of the initial morphology detonation nanodiamond (DND) has been focus many research studies that aim to develop a fundamental understanding carbon condensation under extreme conditions. Identifying pathways DND formation potential for significant impact on controlled synthesis nanoscale with tailored functionality; currently, wide range possible (and conflicting) mechanisms nucleation and growth have proposed, further is essential. Building comprehensive challenging because...
We explore the structural evolution of highly oriented pyrolytic graphite (HOPG) under detonation-induced shock conditions using in situ synchrotron x-ray diffraction ns timescale. observe formation hexagonal diamond (lonsdaleite) at pressures above 50 GPa, qualitative agreement with recent gas gun experiments. First-principles density functional calculations reveal that uniaxial compression, energy barrier for transition toward is lower than cubic diamond. Finally, no indication was...
Fully synthetic peptoid membranes are known to mimic important features of biological membranes, with several advantages over other biomimetic membranes. A fundamental understanding how the individual amphiphiles assemble in solution form bilayer membrane is key unlocking their versatility for application a broad range processes. In this study, situ X-ray scattering and molecular dynamics simulations used understand early stages assembly three different peptoids that exhibit distinctly...
Type III deep eutectic solvents (DES) have attracted significant interest as both environmentally friendly and functional that are, in some ways, advantageous to traditional aqueous systems. While these continue produce remarkable thin films nanoparticle assemblies, their interactions with metallic surfaces are complex difficult manipulate. In this study, the near-surface region (2–600 nm) of a carbon surface is investigated immediately following silver nucleation growth. This accomplished,...
Sputter deposition of B4C films with tailored physical properties remains a challenge. Here, we systematically study how substrate temperature influences the deposited by direct current magnetron sputtering onto planar substrates held at temperatures in range 100−510°C. Results show that all are amorphous stoichiometric B4C, low O content ∼1 at. %. Films 100°C exhibit high compressive residual stress and decreased mechanical properties. For elevated 180−510°C, film mass density, surface...
Hafnia is a high refractive index material used in the manufacturing of dielectric coatings for next generation lasers. The formation defects during deposition major barrier to realizing laser-damage resistant future energy density laser applications. Understanding precursors responsible laser-induced damage hafnia therefore critical. In this work, we investigate mechanism 90-nm thick films produced by an oxygen assisted dual ion beam sputtering (IBS) process. Under pulsed, nanosecond...
The deposition of thick B4C films with low residual stress by conventional direct-current magnetron sputtering is accompanied the formation dust particulates contaminating target, chamber, and substrates leading to nodular defects in films. Here, we demonstrate that greatly reduced during radio-frequency (RFMS). We systematically study properties deposited RFMS a substrate temperature 330 °C, target-to-substrate distance 10 cm, Ar working gas pressure range 4.5–12.0 mTorr (0.6–1.6 Pa), tilt...