Bulletin of the American Physical Society
2021 Virtual Conference for Undergraduate Women in Physics
Friday–Sunday, January 22–24, 2021; Virtual
Session U01: Solid State Materials and Applied Physics IInteractive Live
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Chair: Qiuzi Li, Exxon Mobil Corporation |
Sunday, January 24, 2021 12:00PM - 12:10PM |
U01.00001: AB2(O/F)6 Compounds and the Stabilization of Trirutile Ruining Zhang, Emily Schueller, Yuzki Hey, William Zhang, Ram Seshadri, Kyle Miller, James Rondinelli The properties of crystalline materials tend to be strongly correlated with their structures, and the prediction of crystal structure from only the composition is a coveted goal in the field of inorganic materials. However, such predictions normally rely on a complex network of interactions and the orthodox method—density functional theories calculations—despite its accuracy, involve high computational and time toils. This research investigates the effectiveness of machine learning methods for structure prediction and searches for new potential compounds. Specifically, we focus on the AB2(O/F)6 composition space with the goal to predict new compounds in the trirutile family. Machine learning methods reduce the time and computational expenses of the search by narrowing down the range of compounds for which density functional theory (DFT) calculations are performed. We predict 18 candidates, previously unreported trirutile oxides. We attempt to prepare two of these and show they form in the disordered rutile structure. Additionally, we develop an understanding of how geometric and bonding constraints determine the crystallization of AB2(O/F)6 compounds in the trirutile structure as opposed to other ternary structures in this space. [Preview Abstract] |
Sunday, January 24, 2021 12:10PM - 12:20PM |
U01.00002: Determining fitness of Au$_{\mathrm{x}}$Al$_{\mathrm{1-x}}$ thin films for use in surface plasmon resonance sensors Molly Kate Kreider, Abdul Qadeer Rehan, Robert Kent, Mariama Rebello Sousa Dias Metals exhibiting well-defined surface plasmon resonance (SPR) responses form the basis for SPR sensing devices that work to analyze a medium by detecting minute changes to its index of refraction. Au works particularly well for such a device due to its highly sensitive and sharp minima in its reflectance spectra. Other materials, such as Al, also exhibit defined SPR responses, though Al is not ideal for application in sensing because of its tendency to oxidize. In this work, we analyze the SPR response for both fixed incident angle and fixed incident wavelength of pure Al, pure Au, and 4 Au-Al bimetallic thin films to determine their capability for application in sensing devices. These films were fabricated using the co-sputtering deposition method and then given a temperature treatment. Specifically, for each film at four different thicknesses, we analyze the sensitivity of the location of the reflectance dip as well as two qualities pertaining to the shape of the graph, the full width at half maximum (FWHM) and the peak height. Performing a full analysis yielded that generally, the alloys outperformed the pure films for fixed incident angles, at the expense of a markedly larger FWHM. However, Au$_{\mathrm{0.85}}$Al$_{\mathrm{0.15\thinspace }}$was more sensitive than pure Au and Al in every configuration while maintaining a comparable peak height and FWHM and without exhibiting any oxidation, suggesting it may be suitable for application in sensing devices. [Preview Abstract] |
Sunday, January 24, 2021 12:20PM - 12:30PM |
U01.00003: Dielectric elastomer actuators: impact of foam tape density on flexibility and feasibility of future prosthetics Lydia Guertin In light of the expanding field of medical soft robotics and the need to replicate more accurately the fluidity of human motion in prosthetic tissues, researchers have begun exploring dielectric elastomer actuators as a possible replacement for the current prosthetic technological failures. This paper explores the structural support failings of current models of actuators and posits the use of a similar dielectric tape, VHB 5952, in the fashion of current experimental research on VHB tapes. While this tape significantly increases structural support and reduces the potential for tearing in the prosthetic tissue, it is found to be incompatible with the low voltage requirements of a mechanism working in the human body. The conclusion reached of the impossibility of VHB 5952 is used to recommend a possible middle ground between the industry standard of VHB 4910 and increased structural integrity to advance the field of prosthetic engineering. [Preview Abstract] |
Sunday, January 24, 2021 12:30PM - 12:40PM |
U01.00004: Set up of a pumping system using 3D printing for microfluidics studies Luisa Pires Ferreira, Varlei Rodrigues, Vladimir Gaal \begin{document} \\ Microfluidics deals with the manipulation of fluidics inside channels with micrometric cross-section dimensions, allowing for laminar flow transport. It has multidiscipline applications, attracting the attention of different fields. \\ Before, microfluidic research required clean rooms and specific equipment to create the channels. However, they have been substituted by polymer modeling using 3D print. For this project we produced microfluidic devices with lactic polyacid (PLA), a polymer made with renewable sources (such as sugar cane and maize starch), that allows for 3D printing. This fabrication technique also allows for easy and fast reproducibility. \\ The commercial pumping systems, usually used in this field of study, have a high price in the market and show some research application restrictions. Looking for independent flux control in multiple entrance devices and lower prices, we created a pump that fits our needed criteria in this work. It utilizes Arduino programming to control the flux in three independent fluids exits and 3D printing for creating its pieces. \end{document} [Preview Abstract] |
Sunday, January 24, 2021 12:40PM - 12:50PM |
U01.00005: Computational Modeling of Zinc Blende Crystal Growth Joy Hendrix Computational modelling of crystal systems is a useful tool for understanding the mechanisms of crystal formation. Zincblende (cF8-ZnS) was studied as a practice structure because of its relative simplicity, to test the effectiveness of methods that can later be applied to more complex structures, such as spinel. This report discusses principal component analysis (PCA; a machine learning process) and bond angle analysis done on cF8-ZnS trajectories, and also some preliminary studies of spinel (cF56-Al$_{\mathrm{2}}$MgO$_{\mathrm{4}})$. The most notable quality of the cF8-ZnS trajectories is that twinned crystal systems form very easily under these parameters. The tests on cF8-ZnS indicate that these ways of analysis are promising for usage on more complex structures, although modifying certain tools, such as the bond angle analysis code, will be useful for further studies on spinel. [Preview Abstract] |
Sunday, January 24, 2021 12:50PM - 1:00PM |
U01.00006: Monte Carlo Simulations of Electron and Phonon Thermalization in Graphene at the Diffusive-Ballistic Crossover Point Sophie Li The ability to detect single photons has applications in a wide range of disparate fields. One approach for pushing the limits of single-photon detector (SPD) energy resolution is to exploit the temperature rise in a low-heat capacity material upon absorption of a photon. A collaboration between the research groups of Prof. Michael Roukes and Prof. Stevan Nadj-Perge has developed a novel thermal detector based on graphene, due to its attractive electrical, thermal and material properties. In contrast to most existing graphene thermal detectors, this SPD accesses the novel regime in which the mean free path of charge carriers exceeds the dimensions of the flake. In this regime, boundary scattering dominates the behavior of phonons and electrons and determines the temperature distribution across the graphene flake. By way of Monte Carlo simulations, we have quantified the effect of diffuse scattering and specular reflections for circular and rectangular flake boundaries. The results strongly support existing literature regarding phonon heat transfer and surface scattering. [Preview Abstract] |
Sunday, January 24, 2021 1:00PM - 1:10PM |
U01.00007: Silica aerogel as a particle filter in heavy ion detectors Cincia Tsai We investigate the use of high porosity silica (SiO$_{\mathrm{2}})$ aerogel as a particle filter in heavy ion detectors to discriminate between electrons and positive ions. Our prototype device consists of silica aerogel grown in stainless steel micro-mesh that is designed to optimize electron transmission while absorbing positive ions. The samples are produced by the supercritical drying of alcogel (SiO$_{\mathrm{2}}$ matrix suspended in methanol) imbibed in the micro-mesh, producing aerogel that fills the holes of the mesh. We then characterize the aerogel-filled mesh for homogeneity and electronic transparency using scanning electron and transmission electron microscopy (SEM and TEM). SEM analysis indicates that aerogel fills the mesh holes but is susceptible to damage resulting in partially unfilled mesh holes. TEM analysis indicates that electron transmission through aerogel-filled mesh holes is approximately half that of transmission through empty mesh holes. Moving forward, we will examine the effects of altering porosity and the amount of catalyst in the alcogel solution to improve the aerogel robustness and therefore its filling fraction and uniformity in the mesh. [Preview Abstract] |
Sunday, January 24, 2021 1:10PM - 1:20PM |
U01.00008: Spontaneous Polarization in BiGaO3 Joy Wanjiku Wanjiku Joy Njoki,1 Elicah Wabululu,1, 2 Carolyne Songa,1 and James Sifuna1, 3 1Department of Natural Science, The Catholic University of Eastern Africa, 62157 - 00200, Nairobi, Kenya. 2Physics department, Kenyatta University, 43844-00100 , Nairobi, Kenya. 3Materials Modeling Group, Department of Physics and Space Sciences, The Technical University of Kenya, 52428-00200, Nairobi, Kenya. (Dated: September 5, 2020) It is imperative to note that at elevated temperatures, BiGaO3 is a symmetric faced-centered cubic (FCC) and does not display electric polarity. As the temperature decreases, the lattice shrinks and the symmetric arrangement is no longer stable. Shifting of the Ga4$+$ and O2?? ions causes the structure to be altered, creating strain and electric dipoles. The authors herein seek to find out the distortion ratio, also called the spontaneous strain (Ss) that will yield an electric dipole. This polar lattice arrangement forms the ferroelectric phase of the perovskite, which exists at lower temperatures and Is essentially very crucial in sensors. All the calculations are carried out in the framework of density functional theory as implemented in the Siesta method. This work is significant in the sense that it shows how a material can easily change from one ferroelectric state to another and back. Key words: Polarization, BiGaO3, Spontaneous [Preview Abstract] |
Sunday, January 24, 2021 1:20PM - 1:30PM |
U01.00009: Title: First principles study of sigma phase destabilization in compositionally-complex stainless steel alloys Anna Soper, Savanah Diaz, Holly Frank, Jonas Kaufman, Adam Shaw, Kevin Laws, Aurora Pribram-Jones, Lori Bassman Stainless steels are used in industry extensively due to a combination of desirable material properties, such as corrosion resistance and strength. However, ferritic steels form a brittle sigma phase at moderately high temperatures which limits their utility. Building on experimental findings that small amounts of Al in the presence of Mn suppress the formation of the Fe-Cr sigma phase, this first principles work explores the hypothesis that Al disrupts sigma geometry by changing the electron distribution among the crystal's molecular orbitals. In order to investigate this, a generalized cluster expansion combined with Monte Carlo simulations are used to determine the preferential placement of atomic species on each basis site at appropriate annealing temperatures. Analytical methods, including the Crystal Orbital Hamilton Population method, will be used in future work to determine the ways in which Al destabilizes the sigma structure. [Preview Abstract] |
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