NSF REU Physics Students
Front Row (Left to Right):): Allison Savage, University of Iowa, Samantha Combs, Eckerd College; Middle Row: Greg Hoth, Reed College, Weldu Gebremichael, UNLV, Markus Vasquez, Oklahoma State University, Martin Galley, SUNY-Cortland; Top Row: Brant Abeln, Drake University, Louis Prahl, Lewis and Clark University, Lucas Wilson University of Wisconsin-Stevens Point, Mike Brawner, UNLV.
Brandt Abeln, Drake University
mentor, Andrew Cornelius, associate professor
Correlated-electron systems are so named because there are strong interactions between electrons unlike traditional metals such as copper that have “free electrons” which interact very weakly with each other. Studies on correlated-electron systems have wide ranging interest from defense related issues to future use in nanoscale devices. In some of these systems, unconventional superconductivity emerges out of the suppression of magnetism. The magnetic system U3Bi4Rh3 is going to be studied as a possible candidate for superconductivity.
Samantha Combs, Eckerd College
mentor, Malcolm Nicol, professor
Density of States of Iron Solid Solutions at Ambient and High Pressures using Nuclear Resonant Inelastic X-ray Scattering
Nuclear resonant inelastic x-ray scattering (NRIXS) of synchrotron radiation uses the energy transferred during the inelastic nuclear absorption of photons to determine phonon density of states for solid Mössbauer isotopes. This type of experiment can be conducted at ambient and high pressures with the use of a diamond anvil cell (DAC) and a rhenium gasket. Here, we are concerned with the phonon DOS of α-FePt 10% at pressures up to 30 GPa, as well as FeAl 4.3%, 6.4%, and 27.1% at ambient pressures. The iron samples used are doped in order to increase the pressure at which the alpha to epsilon phase transition for iron occurs. As the most abundant element within Earth’s core, the study of iron is fundamental in geophysics and in terms of thermodynamic modeling.
Mike Brawner, UNLV and Greg Hoth, Reed College
mentor, Pamela Burnley, associate research professor
We are studying how the mineral fayalite deforms under stress while it is subject to high pressures and temperatures. Specifically, we are analyzing x-ray diffraction spectra obtained from experiments with the D-DIA apparatus at Brookhaven national labs. By fitting peaks to the diffraction spectra, we can calculate the spacing between lattice planes of fayalite and so we can observe how this spacing changes over time as the crystal structure deforms We hope to show that this deformation can be modeled using an Elastic Plastic Self Consistent model. In such a model, the material is treated as a cluster of independently oriented grains. When stress is applied to the material, deformation takes place because the lattice planes can slip by each other. A variety of slip systems are used to model the different ways these planes can move. The model allows us to calculate the aggregate properties of the material from the microscopic properties of the individual grains.
Martin Galley, SUNY-Cortland
mentor, Michael Pravica, assistant professor
We performed Raman spectroscopic studies of 1,3,5,7-cyclooctatetraene at elevated pressures up to 10 GPa with the aim of examining possible planarization of the molecule and further studying two prior-discovered phases of the solid with pressure. The Raman excitation source was a Krypton-ion laser operating at 674.1 nm (give wavelength).
Weldu Gebremichael, UNLV
mentor, Andrew Cornelius, associate professor
Study of Thermoelectric Materials at High Pressure
Abstract: It is of extreme importance to develop new potential energy sources to reduce dependence on fossil fuels. As a result of this, the study of thermoelectric materials, capable of changing heat into electrical energy, has become a field of great interest regarding fundamental properties. To help better understand these materials, facilities for the measurement of relevant properties at high pressure have been developed, but lack the ability to characterize the materials at high temperature and pressure. Therefore, this project has the goal of developing a heater arrangement to be used in conjunction with the high pressure capabilities already developed to fully characterize these materials.
Louis Prahl, Lewis and Clark University
mentor, David Shelton, professor
Determination of Ferroelectric Properties in Carbohydrate Glasses Using Atomic Force Microscopy
Piezoelectric Force Microscopy (PFM) is a variant of Atomic Force Microscopy, in which a voltage is applied to the scanning tip, and tip-surface interactions are used to map regions of localized dipole orientation in a sample, called ferroelectric domains. This technique will be used to image domains in capacitor dielectric ceramic material (Barium Strontium Titanate), and then applied to map domains in carbohydrate glasses. The advantage of a molecular glass is that it “freezes” the liquid phase in place, potentially allowing us to image domain structures. Hyper-Rayleigh Scattering experiments have indicated evidence of localized domain formation in polar liquids, and carbohydrates are possible candidates for this effect.
Allison Savage, University of Iowa
mentor, Oliver Tschauner, associate research professor
Spatially resolved optical absorption spectrometry and single crystal diffraction on metamict materials. The goal is to identify and characterize polyamorphisms metamict glasses. Further, we examine the hypothesis that pyrochlores do not amorphise but undergo a structural transition upon metamictization this part of the project will be conducted at the APS.
Markus Vasquez, Oklahoma State University and Lucas Wilson, University of Wisconsin, Stevens Point
mentor, John Farley, professor
The Study of Spinels by Laser Micro-Raman Spectroscopy
Standards of spinels, composed of two metals and oxygen with the formula AB2O4, are being created with known composition to identify spinels in samples of unknown composition by comparison with the spectra obtained from the standards. Laser micro-Raman spectroscopy allows the identification of chemical species based on their unique vibrational modes. The degree to which spinels of varying composition can be identified will be determined. This will aid in the study of the corrosion of steel by liquid metal. Spinels are a likely component of the oxide layer. Understanding the composition of the products of corrosion leads to an understanding of the processes involved in corrosion. This work is vital to the transmutation of nuclear waste.