ORCID Profile
0000-0002-0962-371X
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Publisher: Wiley
Date: 30-12-2022
Abstract: Oxides that exhibit an insulator–metal transition can be used to fabricate energy‐efficient relaxation oscillators for use in hardware‐based neural networks but there are very few oxides with transition temperatures above room temperature. Here the structural, electrical, and thermal properties of V 3 O 5 thin films and their application as the functional oxide in metal/oxide/metal relaxation oscillators are reported. The V 3 O 5 devices show electroforming‐free volatile threshold switching and negative differential resistance (NDR) with stable ( % variation) cycle‐to‐cycle operation. The physical mechanisms underpinning these characteristics are investigated using a combination of electrical measurements, in situ thermal imaging, and device modeling. This shows that conduction is confined to a narrow filamentary path due to self‐confinement of the current distribution and that the NDR response is initiated at temperatures well below the insulator–metal transition temperature where it is dominated by the temperature‐dependent conductivity of the insulating phase. Finally, the dynamics of in idual and coupled V 3 O 5 ‐based relaxation oscillators is reported, showing that capacitively coupled devices exhibit rich non‐linear dynamics, including frequency and phase synchronization. These results establish V 3 O 5 as a new functional material for volatile threshold switching and advance the development of robust solid‐state neurons for neuromorphic computing.
Publisher: Walter de Gruyter GmbH
Date: 25-08-2020
Abstract: In this contribution, the relaxation and diffusional behaviors of low viscous fluids, water and methanol confined into mesoporous silica and controlled size pore glass were investigated. The engineered porous systems are relevant to geologically important subsurface energy materials. The engineered porous proxies were characterized by Brunauer–Emmett–Teller (BET) surface analyzer, nuclear magnetic resonance (NMR) spectroscopy, and electron microscopy (EM) to determine surface area, pore-wall protonation and morphology of these materials, respectively. The confined behavior of the low viscous fluids was studied by varying pore diameter, fluid-to-solid ratio, temperature, and pressure, and then compared to bulk liquid state. Both relaxation and diffusion behaviors for the confined fluids showed increasing deviation from pure bulk fluids as the fluid-to-solid ratio was decreased, and surface-to-volume ratio ( S / V ) was varied. Variable pressure deuteron NMR relaxation of confined D 2 O and confined methanol, deuterated at the hydroxyl or methyl positions, were performed to exploit the sensitivity of the deuteron quadrupole moment to molecular rotation. The methanol results demonstrated greater pressure dependence than those for water only in bulk. The deviations from bulk liquid behavior arise from different reasons such as confinement and the interactions between confined fluid and the nano-pore wall. The results of the present report give insight into the behavior of low viscosity fluid in nano-confined geometries under different state conditions.
Location: United States of America
Location: Puerto Rico
No related grants have been discovered for Armando Rua.