36 research outputs found

    Agency, design and ‘slow democracy’

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    Can democracy be resilient in an increasingly ‘high-speed society’? Social acceleration, some critics argue, poses a serious threat to the idea and practice of democracy. Others invoke but do not develop the idea of ‘slow democracy’ as one important response to this threat. Despite its importance, the critique and response lack analytical depth. In this context, and in an effort to rebuild the debate on a stronger and more fruitful base, the article underscores the potential of political agency to shape democracy’s temporality and reframes ‘slow democracy’ as a challenge of democratic design

    Low-Dimensional Polyoxometalate Molecules/Tantalum Oxide Hybrids for Non-Volatile Capacitive Memories

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    Transition-metal-oxide hybrids composed of high surface-to-volume ratio Ta2O5 matrices and a molecular analogue of transition metal oxides, tungsten polyoxometalates ([PW12O40]3-), are introduced herein as a charge storage medium in molecular nonvolatile capacitive memory cells. The polyoxometalate molecules are electrostatically self-assembled on a low-dimensional Ta2O5 matrix, functionalized with an aminosilane molecule with primary amines as the anchoring moiety. The charge trapping sites are located onto the metal framework of the electron-accepting molecular entities as well as on the molecule/oxide interfaces which can immobilize negatively charged mobile oxygen vacancies. The memory characteristics of this novel nanocomposite were tested using no blocking oxide for extraction of structure-specific characteristics. The film was formed on top of the 3.1 nm-thick SiO2/n-Si(001) substrates and has been found to serve as both SiO2/Si interface states' reducer (i.e., quality enhancer) and electron storage medium. The device with the polyoxometalates sandwiched between two Ta2O5 films results in enhanced internal scattering of carriers. Thanks to this, it exhibits a significantly larger memory window than the one containing the plain hybrid and comparable retention time, resulting in a memory window of 4.0 V for the write state and a retention time around 104 s without blocking medium. Differential distance of molecular trapping centers from the cell's gate and electronic coupling to the space charge region of the underlying Si substrate were identified as critical parameters for enhanced electron trapping for the first time in such devices. Implementing a numerical electrostatic model incorporating structural and electronic characteristics of the molecular nodes derived from scanning probe and spectroscopic characterization, we are able to interpret the hybrid's electrical response and gain some insight into the electrostatics of the trapping medium. © 2016 American Chemical Society

    Molecular junctions made of tungsten-polyoxometalate self-assembled monolayers: Towards polyoxometalate-based molecular electronics devices

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    In this work, the electrical conduction of planar Au junctions electrically bridged by a polyoxometalate-based self-assembled monolayer, aimed to be used in hybrid silicon/molecular memory devices, is discussed. Tunnelling assisted by the presence of polyoxometalate anions is recognised as the main conduction mechanism for these devices. Fluctuations and hysteresis that are profoundly observed in the current-voltage characteristics for the smallest junctions suggest that the anions number is the more crucial factor in the devices behaviour. Quantitative analysis of the obtained characteristics based on Simmons's model reveals an increase in the tunnelling barrier height as the electrode distance increases from 20 to 200 nm. (C) 2011 Elsevier B.V. All rights reserved
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