A5038713032- Nuclear Materials and Properties
- Nuclear reactor physics and engineering
- Acoustic Wave Phenomena Research
- Adhesion, Friction, and Surface Interactions
- High-pressure geophysics and materials
- Nuclear materials and radiation effects
- Acoustic Wave Resonator Technologies
- Plant and Biological Electrophysiology Studies
- Nuclear Physics and Applications
- Thermodynamic and Structural Properties of Metals and Alloys
- Phase-change materials and chalcogenides
- Photonic and Optical Devices
- Thermography and Photoacoustic Techniques
- Metamaterials and Metasurfaces Applications
- High Entropy Alloys Studies
- Advanced Sensor Technologies Research
- High-Temperature Coating Behaviors
- Fusion materials and technologies
- Hydrogen Storage and Materials
- Microfluidic and Bio-sensing Technologies
- Polymer Surface Interaction Studies
- Advanced materials and composites
- Photorefractive and Nonlinear Optics
- Seismic Waves and Analysis
- Optical and Acousto-Optic Technologies
Idaho National Laboratory
2019-2024
University of California, San Diego
2018-2021
University of Washington
2015-2019
Massachusetts Institute of Technology
2015
Indian Institute of Technology Indore
2012
Reconfiguration of silicon photonic integrated circuits relying on the weak, volatile thermo-optic or electro-optic effect usually suffers from a large footprint and energy consumption. Here, integrating phase-change material, Ge2Sb2Te5 (GST) with microring resonators, we demonstrate an energy-efficient, compact, non-volatile, reprogrammable platform. By adjusting number free-space laser pulses applied to GST, characterize strong broadband attenuation optical phase modulation effects...
Contact-based vibrations play an essential role in the dynamics of granular materials. Significant insights into vibrational have previously been obtained with reduced-dimensional systems containing macroscale particles. We study contact-based a two-dimensional monolayer micron-sized spheres on solid substrate that forms microscale crystal. Measurements resonant attenuation laser-generated surface acoustic waves reveal three collective modes involve displacements and rotations microspheres,...
Advanced nuclear reactor concepts aim to use fuels that must withstand unprecedented temperature and radiation extremes. In these fuels, thermal energy transport under irradiation is directly related fuel longevity, safety, arguably one of the most important performance metrics. Here we provide a comprehensive, first-principles-informed treatment phonon mediated in defect-bearing actinide oxide with direct comparison experimental measurements. Pristine proton irradiated thorium dioxide was...
We report the design and characterization of a self-assembled, locally resonant acoustic metamaterial for Lamb waves, composed monolayer $1.02$ $\mu$m polystyrene microspheres adhered to $1.3$ thick free-standing silicon membrane. A laser-induced transient grating technique is used generate waves in measure its response. The measurements reveal microsphere contact resonance lowest frequency spheroidal resonance. measured dispersion curves show hybridization flexural with compare an...
Thermal transport is a key performance metric for thorium dioxide in many applications where defect-generating radiation fields are present. An understanding of the effect nanoscale lattice defects on thermal this material currently unavailable due to lack single crystal from which unit processes may be investigated. In work, series high-quality crystals exposed 2 MeV proton irradiation at room temperature and 600 °C create microscale regions with varying densities types point extended...
We present a method for the recovery of complex wavenumber information via spatial Laplace transforms spatiotemporal wave propagation measurements. The aids in analysis acoustic attenuation phenomena and is applied three different scenarios: (i) Lamb-like modes air-saturated porous materials low kHz regime, where enables viscoelastic parameters; (ii) Lamb Duralumin plate MHz demonstrates effect leakage on splitting forward S1 backward S2 around Zero-Group Velocity point; (iii) surface waves...
Phonon lifetimes are a key component of quasiparticle theories transport, yet first-principles rarely directly compared to inelastic neutron scattering (INS) results. Existing comparisons show discrepancies even at temperatures where perturbation theory is expected be reliable. In this work, we demonstrate that the reciprocal space voxel ($q$-voxel), which finite region in required INS data analysis, must explicitly accounted for within order draw meaningful comparison. We accurate...
Multi-principal component transition metal (TM) diborides represent a class of high-entropy ceramics (HECs) that have received considerable interest in recent years owing to their promising properties for extreme environment applications include thermal/ environmental barriers, hypersonic vehicles, turbine engines, and next-generation nuclear reactors. While the addition chemical disorder through random distribution TM elements on cation sublattice has offered opportunities tailor elastic...
We present a modification of the laser-induced transient grating setup enabling continuous tuning period. The fine control period is accomplished by varying angle diffraction used to split excitation and probe beams. has been tested measuring dispersion bulk surface acoustic waves in both transmission reflection geometries. presented fully compatible with optical heterodyne detection can be easily implemented any setup.
The quasiharmonic approximation (QHA) is the simplest nontrivial for interacting phonons under constant pressure, bringing effects of anharmonicity into temperature-dependent observables. Nonetheless, QHA often implemented with additional approximations due to complexity computing arbitrary strains, and generalized QHA, which employs stress boundary conditions, has not been completely developed. Here we formulate providing a practical algorithm strain state other observables as function...
Attenuation of surface acoustic waves (SAWs) by a disordered monolayer polystyrene microspheres is investigated. Surface wave packets are generated pair crossed laser pulses in glass substrate coated with thin aluminum film and detected via the diffraction probe beam. When 170 μm-wide strip micron-sized spheres placed on between excitation detection spots, strong resonant attenuation SAWs near 240 MHz observed. The caused interaction contact resonance microspheres, as confirmed dispersion...
Longitudinal contact-based vibrations of colloidal crystals with a controlled layer thickness are studied.
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Corrosion of aluminium alloy clad nuclear fuel, during reactor operation and under subsequent wet storage conditions, promotes the formation hydroxide oxyhydroxide layers. These hydrated mineral phases chemisorbed physisorbed waters on their surfaces are susceptible to radiation-induced processes that yield molecular hydrogen gas (H2), which has potential complicate long-term disposal fuel through flammable explosive mixture formation, embrittlement, pressurization. Here, we present a...
We report the adiabatic elastic constants of single-crystal thorium dioxide over a temperature range 77–350 K. Time-domain Brillouin scattering, an all-optical, non-contact picosecond ultrasonic technique, is used to generate and detect coherent acoustic phonons that propagate in bulk perpendicular surface crystal. These lattice vibrations have been monitored two hydrothermally grown samples along (100) (311) crystallographic directions. The three independent cubic crystal (C11, C12, C44)...
In this work, impact of low level uranium (U) atom substitution on thermal conductivity thorium dioxide (ThO2) is investigated. ThO2 an electronic insulator with a wide optical band-gap and no unpaired electrons whose transport governed by phonons. U-substitution introduces f-electrons resulting in paramagnetic behavior UThO2 at room temperature, which significantly suppresses its conductivity. A single crystal graded composition U grown using hydrothermal synthesis method, measurements are...
Neodymium iron boron magnet has registered heightened demand due to its rapidly increasingly application in the clean energy sector. These magnets are manufactured by melting mixture, consisting of neodymium, and followed casting into ingots. The ingots subsequently pulverized powder, which, turn, is sintered magnetized form permanent magnet. An alternative approach controlled addition neodymium master alloy fabricate present process discusses an novel electrochemical prepare neodymium-iron...
The ultrafast dynamics of the antiferrodistortive phase transition in perovskite SrTiO3 is monitored via time-domain Brillouin scattering. Using femtosecond optical pulses, we initiate a thermally driven tetragonal-to-cubic structural transformation and detect crystal through changes frequency oscillations (BO) induced by propagating acoustic phonons. Coupling measured BO with spatiotemporal heat diffusion model, demonstrate that, for sample kept tetragonal phase, deposition sufficient...