Bulletin of the American Physical Society
2018 Annual Spring Meeting of the APS Ohio-Region Section and the AAPT Michigan Section
Volume 63, Number 7
Friday–Saturday, March 23–24, 2018; East Lansing, Michigan
Session E2: Contributed: Applied Physics and Materials Science I |
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Room: Biomedical and Physical Sciences Building 1420 |
Saturday, March 24, 2018 10:15AM - 10:27AM |
E2.00001: Mechanism of Auxetic Structures Designed and Fabricated with 3D Printer Martha Mata, Xin Du Metamaterials are bulk objects with special mechanism properties defined by their repetitive inner structures, rather than the materials they are made of. One of the special mechanisms is ``auxetic behavior'': when the materials are stretched in one direction, unlike conventional materials, they will also expand in the lateral direction. In this project we studied the dependence of Poisson's Ratio on the geometric parameters of auxetic structures. We used 3-D printer to efficiently design and produce honeycomb auxetic structures. With an innovative experimental setup and image analysis techniques, we are able to study the pulling force and the corresponding lateral expansion of auxetic structures with various geometric parameters. Also, we found a linear relationship between the Poisson's Ratio and the geometric parameter of the honeycomb auxetic structure. Our result is consistent with theoretical analysis. [Preview Abstract] |
Saturday, March 24, 2018 10:27AM - 10:39AM |
E2.00002: Intriguing photoconductivity in bulk oxides at room temperature Pooneh Saadatkia, Petr Stepanov, Farida Selim Complex oxides with the ABO3 perovskite crystal structure reveal a range of spectacular phenomena such as superconductivity, ferroelectricity, and metal-insulator transitions. SrTiO3 (STO) has been the focus of intense research in the world of oxide materials due to its functional, dielectric and ferroelectric properties. In this work, Hall and photo-Hall measurements have been carried out on a number of as-grown STO samples provided from different suppliers to investigate the photo-response of bulk STO single crystals and its dependence on photon energy and intensity. Most of samples were photoconductive at room temperature but no persistent photoconductivity was observed. Vacancies are known to be dominant defects in perovskite oxides and significantly affect the material properties. Therefore, identifying the nature of vacancy defects is crucial to understand the origin of these novel photoconductivity phenomena in complex oxides in STO bulk single crystals. Positron annihilation lifetime spectroscopy and digital coincidence Doppler broadening spectroscopy were applied to examine the presence of defects. The measurements revealed the strong dependence of photoconductivity on defect concentration under illumination of sub band gap visible light. [Preview Abstract] |
Saturday, March 24, 2018 10:39AM - 10:51AM |
E2.00003: Using Match Stick Arrays to Analyze Forest Fire Propagation Along a Slope Abigail Ambrose, Niklas Manz The effect of a forest floor slope $\theta $ on the propagation speed $v$ of forest fires was experimentally analyzed using physical, 3D-printed models with match stick arrays to represent the trees. Various models for three specific distance conditions between neighboring match heads were created. In each model type the distance between the match heads $\Delta d$ is kept constant along the horizontal ($x$-model), along the vertical ($z$-model), and along the slope ($r$-model). For all three models, the slope-speed relationship $v(\theta )$ along the incline for both, the upward and downward propagation of the fire fronts was determined by measuring the time the front needed to propagate through the length of the model. Each model was best fit with a different mathematical function: the $x$-model with an exponential curve, the $z$-model with a quadratic curve, and the $r$-model with a straight line. [Preview Abstract] |
Saturday, March 24, 2018 10:51AM - 11:03AM |
E2.00004: ZnO Films Printed by Inkjet and Aerosol Jet Techniques for Flexible Electronics David Winarski, Eric Kreit, Emily Heckman, Erik Flesburg, Micah Haseman, Roberto Aga, Farida Selim Zinc oxide (ZnO) thin films have remarkable versatility in flexible electronics applications. Here, we report simple ink synthesis and printing methods to deposit ZnO photodetectors on a variety of flexible and transparent substrates, including polyimide (Kapton), polyethylene terephthalate, cyclic olefin copolymer (TOPAS), and quartz. X-ray diffraction analysis revealed the dependence of the film orientation on the substrate type and sintering method, and ultraviolet--visible (UV--Vis) absorption measurements revealed a band edge near 380 nm. Van der Pauw technique was used to measure the resistivity of undoped ZnO and indium/gallium-codoped ZnO (IGZO) films. IGZO films showed lower resistivity and larger average grain size compared with undoped ZnO films due to addition of In$^{\mathrm{3+}}$ and Ga$^{\mathrm{3+}}$, which act as donors. A 365-nm light-emitting diode was used to photoirradiate the films to study their photoconductive response as a function of light intensity at 300 K. The results revealed that ZnO films printed by aerosol jet and inkjet techniques exhibited five orders of magnitude photoconductivity. These findings indicate that ZnO films are viable options for flexible electronics like photodetectors, and field-effect transistors. [Preview Abstract] |
Saturday, March 24, 2018 11:03AM - 11:15AM |
E2.00005: Fabrication of One Dimensional Photonic Crystal By Sputtering and Sol Gel Methods Nicholas Borucki, Tom Oder TiO$_{2}$ and SiO$_{2}$ are two oxides that offer one of the largest refractive index differences, which could be tailored for various optical device applications. A one dimensional photonic crystal (1-D PC) within the UV-visible spectrum made of thin multilayer films of TiO $_{2}$ and SiO$_{2}$ was fabricated. Two methods of deposition were compared: magnetron sputtering and sol-gel spin coating. The photonic band gap (PBG) was theoretically and experimentally determined by controlling the periodic spacing of the constituent materials. PBG's were observed between 200 – 350 nm in both samples. Furthermore, steps towards making a PC with 2-D and omnidirectional band gaps were investigated. Further details of the fabrication steps as well as the specific results obtained will be presented. [Preview Abstract] |
Saturday, March 24, 2018 11:15AM - 11:27AM |
E2.00006: Optical Properties of Sputter-Deposited Gallium Oxide Thin Films Sundar Babu Isukapati, Tom Oder We report on studies conducted on gallium oxide (Ga$_{\mathrm{2}}$O$_{\mathrm{3}})$ thin films grown on c-plane sapphire substrates by RF magnetron sputtering from a 99.9{\%} pure ceramic target. Single and poly crystalline thin films were obtained by varying the composition of Ar and O$_{\mathrm{2}}$ gas used in the deposition; substrate temperature and post deposition annealing treatment. The optical characteristics were obtained by UV-VIS spectroscopy measurements which yielded transmission of 90 - 95{\%}, optical bandgaps of 4.7- 4.8 eV. Structural characteristics were analyzed through x-ray diffraction measurements. A single diffraction peak at 2$\theta \quad =$ 37$^{\mathrm{o}}$, assigned to the (4 0 1) plane was obtained for a film annealed at 1000 $^{\mathrm{o}}$C for 1hour in N2 atmosphere. An attempt to dope the films using Sn for n-type conductivity was made. Optical bandgaps of 6{\%}, 9{\%} and 10{\%} Sn-doped Gallium oxide films were 4.72, 4.57 and 4.56 eV, respectively. [Preview Abstract] |
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