Sandia National Laboratories, New Mexico


In situ TEM evaluation of thermal and mechanical stability of 3D interface Cu/Nb
Justin Cheng, University of Minnesota
Practicum Year: 2022
Practicum Supervisor: Khalid Hattar, , Center for Integrated Nanotechnologies, Sandia National Laboratories, New Mexico
This project consists of annealing and straining experiments conducted on 3D interface Cu/Nb nanolaminates (3D Cu/Nb) in the TEM. Annealing experiments were performed in-situ in the TEM to evaluate the thermal stability of 3D Cu/Nb and monitor the order in which microstructural changes occur during thermal degradation. Experiments were conducted at low and high-resolution magnifications to capture phenomena occurring at different length scales. Ongoing straining experiments will be conducted on nanopillars of 3D Cu/Nb to reveal the origins of high strength and deformability in this material. Results from these experiments will determine if a size effect exists in 3D Cu/Nb and where dislocations nucleate in the material.
In-situ TEM Mechanical and Thermal Characterization of Cu/Nb Nanolaminates
Justin Cheng, University of Minnesota
Practicum Year: 2021
Practicum Supervisor: Khalid Hattar, , Center for Integrated Nanotechnologies, Sandia National Laboratories, New Mexico
This project aims to uncover the dynamics of deformation and thermal decomposition of Cu/Nb nanolaminates with nanometer resolution. This project comprises nanopillar compression and laser annealing experiments, with footage of both being taken in a transmission electron microscope to directly observe the progression of nano- and atomic-scale deformation and annealing processes. As Cu/Nb is a model system for controllably studying the effects of heterophase interface structure on the thermomechanical stability of nanostructured alloys, insights from this project can be used to shed light on the underpinnings of how interface structure can be manipulated to achieve record strength and thermal stability in nanocrystalline alloys.
X-Ray Spectroscopy of MagLIF Experiments
David Chin, University of Rochester
Practicum Year: 2021
Practicum Supervisor: Eric Harding, Principal Member of the Technical Staff, Pulse Power Science (Organization Number 1683), Sandia National Laboratories, New Mexico
For my practicum, I focused on x-ray spectroscopy of MagLIF experiments. The initial plans for my practicum were to extract the magnetic field from a MagLIF implosion by analyzing the Zeeman splitting in the Lyman alpha emission. We planned on studying previously measured iron spectra generated from iron contaminants in the beryllium liner and then design or adjust an x-ray spectrometer to either improve the spectral resolving power or change the energy range to study a different element. However, the current iron spectra showed differential splitting between the two Lyman alpha emission peaks, showing evidence that we may be able to extract the magnetic field from the current spectra. The primary analysis for my practicum focused on modeling the Lyman alpha emission to constrain the magnetic field. A continuous spectral model, with magnetic field, ion / electron temperature and electron density as free variables, was generated from a spectral grid and used to fit the data with a Bayesian inference routine. Preliminary results indicated a magnetic field of 20 kT. We plan on running additional tests with denser spectral grids as well as fitting additional spectral features, such as the iron helium alpha parent line, to confirm these results. We were also able to perform x-ray spectrometer development and characterization tests using a Manson source. In order to help characterize the energy dispersion relation using absorption edge filters, we performed exposures on a Manson source with multiple source anodes and k-edge filters. Furthermore, to gain an understanding of the spectral resolution of XRS3, we fit the different emission peaks with models based off the intrinsic width of each emission line. Lastly, we performed an extremely high spectral resolution measurement (E/DE > 10,000) to constrain the shape of the intrinsic iron k-alpha emission. These tests characterizing the spectrometer resolution are important for fitting the MagLIF spectra because the spectrometer response must be included in the Bayesian inference fitting routine.
Synthesis of Novel "Unfeasible" Zeolites Through ADOR
Sylvia Hanna, Northwestern University
Practicum Year: 2021
Practicum Supervisor: Tina Nenoff, , Material, Physical & Chemical Sciences (1800), Sandia National Laboratories, New Mexico
I worked on two projects while at Sandia. They are each summarized in respective paragraphs below. I wrote my practicum proposal on Project 1, and I began Project 2 as a collaborative side project when I arrived at Sandia. Project 1: Zeolites are inorganic, porous, crystalline solids which are some of the most widely used industrial materials, applied in catalysis, separations, and sensing. While there are over two million hypothetical zeolites, only 255 exist. Thus, the synthesis of novel zeolites is a challenging task that is important for their broad commercial usage and for understanding more of their fundamental chemistry. A method to synthesize new zeolites, termed the Assembly-Disassembly-Organization-Reassembly (ADOR) process, has become well established in producing novel zeolites that are not feasible through traditional routes. Typically, ADOR takes a preassembled parent zeolite, selectively breaks it apart, and then pieces it back together to form a new daughter zeolite. I worked to employ ADOR to disassemble two different zeolites and combine their layers into one novel zeolite. By implementing two, rather than one, parent zeolite, additional structural diversity can be integrated. Project 2: While metal nanoparticles show increased catalytic reactivity compared to their bulk metal counterparts, particle migration, aggregation, and subsequent deactivation greatly decrease reactivity. To avoid nanoparticle deactivation, porous framework materials with regular cavities can serve as scaffolds for confining metal nanoparticle catalysts into cages where they prefer not to migrate. Additionally, these cages are connected by channels to other pores within the framework which allow access for reactants, products, and other substrates necessary for the given reaction. Zeolites specifically are crystalline porous materials that have been observed to improve the activity of encapsulated metal nanoparticles for acid gas adsorption (NOx and SOx). However, reported metal impregnation methods typically involve complex metal precursors and lengthy time frames, and the resulting nanoparticle location within the zeolite is not always clear. We have developed a new method to design zeolites with size-restricted, impregnated metal nanoparticles, evenly dispersed throughout zeolite layers. This method requires simple metal salts rather than complex metal precursors, takes place in water (green synthesis), runs for a short length of time (3-6 hours), and involves a facile one-pot procedure. Additionally, we observe diverse kinetics of impregnation for eleven different metal salts. Kinetic analysis using the Avrami-Erofeev model indicates that the coordination ability of the metal salt counterion plays a role in the rate of nanoparticle impregnation. As a result of metal impregnation, NOx adsorption was realized. We anticipate that this impregnation method can be broadly generalized for a variety of other metals and applications.
Investigating environmental effects on Si thin film fatigue
Sandra Stangebye, Georgia Institute of Technology
Practicum Year: 2021
Practicum Supervisor: Khalid Hattar, Dr. , Center for Integrated Nanotechnologies, Sandia National Laboratories, New Mexico
My practicum project involved investigating the fatigue properties of silicon (Si) thin films using in situ TEM fatigue testing. The overall goal of the project was to conduct the fatigue experiments within the environmental TEM (ETEM) to study the effect moisture has on stress-induced oxide growth (which can influence the fatigue behavior). The project mainly involved preparing the Si specimens on the push-to-pull devices used for the fatigue tests by floating 50nm thick Si film on top of the device using a drop of water followed by focused ion beam (FIB) release of the gauge. The devices were then tested in a conventional vacuum TEM at different stress amplitude and mean levels to obtain information on fatigue failure. I also worked on a few other side projects while I was there. One project involved analyzing in situ heating TEM experiments on gold-silicon samples to study the Au-Si eutectic reaction in depth. I also conducted in situ straining TEM experiments on gold thin films combined with Automated Crystal Orientation Mapping (ACOM) to study the deformation mechanisms relationship to the starting grain orientation, structure, etc.
solid state Materials at high pressures and temperatures
Sergio Pineda Flores, University of California, Berkeley
Practicum Year: 2019
Practicum Supervisor: Luke Shulenburger, staff scientiest, High Energy Density Physics Theory department, Sandia National Laboratories, New Mexico
My project can be divided into two efforts. The first is the study of FeO's strain curve using various Quantum Monte Carlo wave functions and methods to unambiguously determine the shape of the strain curve. The second is the study of LiF's optical properties at extreme pressures/temperatures using DFT/MD methods and kubo-greenwood formula.
Influence of Chemistry in HMX-based PBX Initiation
Christopher Miller, Georgia Institute of Technology
Practicum Year: 2018
Practicum Supervisor: Cole Yarrington, Dr., 1000, Sandia National Laboratories, New Mexico
This project involves modeling HMX-based polymer bonded explosive misrostructures and how they evolve under shock loading. These 2D simulations were performed using Sandia's Eulerian hydrocode - CTH. The effects of chemistry were modeled and the run-to-detonation distance was calculated as a function of shock pressure.
Shifting the homogeneous phase transition of water to ice VII by manipulating the isentropic loading path
Erin Nissen, University of Illinois at Urbana-Champaign
Practicum Year: 2018
Practicum Supervisor: Daniel Dolan, Dr. , Dynamic Material Properties (1646), Sandia National Laboratories, New Mexico
During this practicum we utilized the versatility of Sandia National Lab’s Thor-64 machine, where a tunable current pulse (80 kV) generates a magnetic drive to isentropically compress a sample of interest. In our case, we were interested in the homogenous phase transition of liquid water to solid ice VII. Previous studies have focused on peak pressure and window material as major factors for the onset of freezing. We took a different approach and looked at the effects of initial temperature and ramp rate. We found that increasing the initial temperature changes the isentropic loading path and results in a much higher phase transition pressure. We also found that decreasing the rap rate, or decreasing the rate of compression, decreased the transition pressure; however, it effected the initial room temperature isentropic loading paths less than the increased initial temperature paths.
Ab-initio MD calculations of material properties at high temperature and pressure
Gil Shohet, Stanford University
Practicum Year: 2018
Practicum Supervisor: Michael Desjarlais, Senior Scientist, Pulsed Power Sciences Center, Sandia National Laboratories, New Mexico
For the practicum project I learned to use the Vasp DFT code for ab initio molecular dynamics. Using this tool, I studied hydrogen under high pressure with two different potentials, looking for the critical point in the liquid-liquid insulator-metal transition and doing conductivity calculations. I also studied the forsterite vapor dome to compute the critical point for this material.
Coupling kinetic to continuum methods for plasma physics in 1-D
Richard Vega, Texas A&M University
Practicum Year: 2018
Practicum Supervisor: Thomas Gardiner, R&D S&E, Physics, 1641, Sandia National Laboratories, New Mexico
The project involved writing 3 codes: a magneto-hydrodynamics (MHD) code, a two-fluid (TF) plasma code, and a particle in cell (PIC) code. With the three working codes, the goal was then to couple PIC to TF in the regime where their traditional applications overlap.
Optical Diagnostics on the Pecos Test Chamber
Daniel Woodbury, University of Maryland, College Park
Practicum Year: 2018
Practicum Supervisor: Adam Harvey-Thompson, Senior technical staff, 01600, Pulsed Power Sciences, Sandia National Laboratories, New Mexico
The Pecos test chamber is used to study laser preheat on MagLIF targets for Z, but in an offline environment that is more accessible in terms of shot rate and diagnostics. This allows much more rapid development of new target designs and preheating platforms that can be benchmarked for performance before fielding on Z, which has a much slower shot rate and higher risk.
In situ experimental development at the Sandia Ion Beam Lab
Cody Dennett, Massachusetts Institute of Technology
Practicum Year: 2017
Practicum Supervisor: Khalid Hattar, Staff Scientist, Radiation Solid Interactions - Sandia Ion Beam Lab, Sandia National Laboratories, New Mexico
Designed and built and in situ, laser-based materials diagnostic for the 6 MV tandem accelerator at the Sandia Ion Beam Lab. Experiment will be used to track the thermal and mechanical properties of materials subject to ion beam irradiation in near real time.
Developing Environmentally Stable Oxides on Metals using Pulsed Laser Irradiation
Samantha Lawrence, Purdue University
Practicum Year: 2014
Practicum Supervisor: David P. Adams, Distinguished Member of the Technical Staff, Org. 1832, Coatings and Surface Engineering, Sandia National Laboratories, New Mexico
Surface laser-irradiation of oxidizing metals such as stainless steel induces a high-temperature chemical reaction between the metal and ambient atmosphere, resulting in the growth of a film composed of elements from the substrate in combination with environmental gasses. Such films are highly colored and may find use as unique authenticity markings in welded components. The practicum research focused on critical experimental studies to develop materials processing methods to ensure sealed components are robust in harsh corrosive and embrittling environments. As it is likely that laser-induced Cr-depletion from stainless steel substrates is the primary cause of corrosion for the oxidized SS 304L, a set of conditions to will control the environmental resistance of alloys subjected to laser processing was predicted. A set of experiments assessed the effectiveness of pre- and post-treatment of SS 304L for reducing Cr dissolution.
Sunshine to Petrol (S2P)
Elizabeth Miller, Northwestern University
Practicum Year: 2012
Practicum Supervisor: Andrea Ambrosini, Senior Member of Technical Staff, Materials, Devices & Energy Tech, Sandia National Laboratories, New Mexico
For the twelve weeks of my practicum, I was part of Sandia National Laboratories’ Sunshine to Petrol (S2P) project. As the United States seeks to become energy-independent, novel methods for sourcing fuels are required. It is not feasible to have an immediate shift to all renewable energy sources, especially in the area of transportation fuels, and thus, easily implementable, renewable energy sources with shorter time scales are needed. The S2P Program aims to fulfill this need by researching thermochemical fuel production fueled by concentrated solar power. The overarching goal of this project is to find materials that can split carbon dioxide and water. Products from these reactions (carbon monoxide and hydrogen, respectively) can then be used as precursors for the manufacture of hydrocarbon fuels. Current materials which have been successful for this purpose such as ceria have been well-studied but are limited in efficiency; thus the search for better performing, thermodynamically and kinetically favorable redox systems must be expanded.
Ab initio simulations of warm, dense deuterium for x-ray scattering
Paul Davis, University of California, Berkeley
Practicum Year: 2010
Practicum Supervisor: Michael Desjarlais, Manager, Diagnostics and Target Physics, Sandia National Laboratories, New Mexico
This project uses Sandia computer systems and simulation tools to study the properties of deuterium under extreme conditions. In particular, MD-DFT simulations were performed and analyzed to compare to recent x-ray scattering experiments that were performed at LLNL.
Streaked Visible Spectroscopic Measurements on the Z Machine
Matthew Gomez, University of Michigan
Practicum Year: 2009
Practicum Supervisor: Mike Cuneo, Manager, , Sandia National Laboratories, New Mexico
A fiber coupled streaked spectroscopic system was set up to be fielded on the Z machine at Sandia National Labs. This diagnostic was used to observe light emission by z-pinch wires during the initial ablation stage. It was also used to observe light emission from a photo-ionized neon gas cell. Future experiments that will utilize this diagnostic include observation of the plasma formed in a post-hole convolute and hydrogen/helium gas cell emission/absorption with applications to white dwarf stars.
Initial Wetting Tests for the Liquid Lithium Divertor (LLD)
Laura Berzak Hopkins, Princeton University
Practicum Year: 2007
Practicum Supervisor: Richard Nygren, Manager, Fusion Technology Department, Sandia National Laboratories, New Mexico
The National Spherical Torus eXperiment (NSTX) at the Princeton Plasma Physics Laboratory (PPPL) intends to install a novel liquid lithium divertor (LLD) prior to the next run campaign. Before the final divertor can be built, design and materials testing must be completed in order to ascertain the parameters for an optimal device. While design work is underway, Sandia is involved in materials testing. The initial wetting tests are an examination of a unique molybdenum foam and the behavior of lithium in its presence. Thermocouple and IR data are gathered from both bench-top and vacuum heating tests of the foam itself. In addition, lithium foil is melted on to the foam and a variety of both qualitative and quantitative data regarding the manner in which the lithium wets the foam is collected.