Browsing by Subject "devices"
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Item Effect of a Herringbone Mesostructure on the Electromechanical Properties of Piezofiber Composites for Energy Harvesting Applications(2017-02) Avazmohammadi, R.; Hashemi, R.; Avazmohammadi, R.Piezoelectric materials are often used in energy harvesting devices that convert the waste mechanical energy into effective electrical energy. Polymer-based piezoelectric composites appear to be promising candidates for use in these devices, as they offer a number of advantages, such as sufficient flexibility and environmental compatibility. However, a major drawback associated with these composites may be that their effective electromechanical properties are usually weaker than those of the piezoelectric constituents used in them. In this paper, we propose a class of polymeric-based piezoelectric composites with a laminated mesostructure that offer improved electromechanical properties over unidirectional piezofiber composites and can even possess stronger electromechanical properties than their piezoelectric constituents for certain modes of operation. We present examples of enhanced properties of these composites including effective piezoelectric charge and voltage coefficients, as well as effective electromechanical coupling factors for two-dimensional operation modes. We conduct an optimization to identify the optimal microstructure for the highest values of the coupling coefficients within this class of composites. Our findings demonstrate the potential in designing piezoelectric composites with a hierarchical structure to achieve significantly amplified electromechanical properties for energy harvesting applications.Item Enhanced Phosphorescence in Dibenzophosphole Chalcogenide Mixed Crystal(2011-06) Kabe, Ryota; Lynch, Vincent M.; Anzenbacher, Pavel; Lynch, Vincent M.The single crystals of 9-phenyl-9-dibenzophosphole chalcogenides {oxide (1), sulfide (2) and selenide (3)} and a mixed crystal of 2 and 3 have been prepared and characterized by X-ray diffraction analysis. Several intermolecular interactions such as pi-pi and Se-H were observed in the mixed crystal of 2 and 3. The mixed crystal of 2 and 3 exhibited enhanced phosphorescence compared to the pure constituent crystal (2 or 3) at low temperature.Item Fifty FDAs: An Argument for Federal Preemption of State Tort Law that is Less than Meets the Eye(2010-01-01) Goodwin, James; Shudtz, Matthew; Shapiro, Sidney A.; McGarity, Thomas O.; Funk, William; Buzbee, William W.Item Heterostructures For Realizing Magnon-Induced Spin Transfer Torque(2012-04) Jayathilaka, P. B.; Monti, M. C.; Markert, J. T.; Miller, C. W.; Monti, M. C.; Markert, J. T.This work reports efforts fabricating heterostructures of different materials relevant for the realization of magnon-induced spin transfer torques. We find the growth of high-quality magnetite on MgO substrates to be straightforward, while using transition metal buffer layers of Fe, Cr, Mo, and Nb can alter the structural and magnetic properties of the magnetite. Additionally, we successfully fabricated and characterized Py/Cr/Fe3O4 and Fe3O4/Cr/Fe3O4 spin valve structures. For both, we observe a relatively small giant magnetoresistance and confirman inverse dependence on spacer layer thickness. Thus, we have shown certainmaterials combinations that may form the heterostructures that are the building blocks necessary to achieve magnon-induced spin transfer torque devices.Item Temperature Dependence Of Brillouin Light Scattering Spectra Of Acoustic Phonons In Silicon(2015-02) Olsson, Kevin S.; Klimovich, Nikita; An, Kyongmo; Sullivan, Sean; Weathers, Annie; Shi, Li; Li, Xiaoqin; Olsson, Kevin S.; Klimovich, Nikita; An, Kyongmo; Sullivan, Sean; Weathers, Annie; Shi, Li; Li, XiaoqinElectrons, optical phonons, and acoustic phonons are often driven out of local equilibrium in electronic devices or during laser-material interaction processes. The need for a better understanding of such non-equilibrium transport processes has motivated the development of Raman spectroscopy as a local temperature sensor of optical phonons and intermediate frequency acoustic phonons, whereas Brillouin light scattering (BLS) has recently been explored as a temperature sensor of low-frequency acoustic phonons. Here, we report the measured BLS spectra of silicon at different temperatures. The origins of the observed temperature dependence of the BLS peak position, linewidth, and intensity are examined in order to evaluate their potential use as temperature sensors for acoustic phonons. (C) 2015 AIP Publishing LLC.