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Instabilities by ionic bombardment  [PDF]
Seyed Reza Mahmoudi,Sushant Anand,Kazimierz Adamiak,G. S. Peter Castle,Kripa K. Varanasi
Physics , 2013,
Abstract: This fluid dynamics video is an entry for the Gallery of Fluid Motion of the 66th Annual Meeting of the APS-DFD. This work reveals new types of interfacial instabilities that occur during forced-spreading of dielectric films subjected to ionic bombardment. We demonstrated that keeping the ionic bombardment strength constant, the appearance of instability patterns dramatically changes by varying viscosity of the bombarded droplet.
Efficient resistive memory effect on SrTiO3 by ionic-bombardment  [PDF]
Heiko Gross,Seongshik Oh
Physics , 2011, DOI: 10.1063/1.3633114
Abstract: SrTiO3 is known to exhibit resistive memory effect either with cation-doping or with high-temperature thermal reduction. Here, we add another scheme, ionic-bombardment, to the list of tools to create resistive memory effect on SrTiO3 (STO). In an Ar-bombarded STO crystal, two orders of resistance difference was observed between the high and low resistive states, which is an order of magnitude larger than those achieved by the conventional thermal reduction process. One of the advantages of this new scheme is that it can be easily combined with lithographic processes to create spatially-selective memory effect.
Compact Electron Gun Based on Secondary Emission Through Ionic Bombardment  [PDF]
Babacar Diop,Jean Bonnet,Thomas Schmid,Ajmal Mohamed
Sensors , 2011, DOI: 10.3390/s110505202
Abstract: We present a new compact electron gun based on the secondary emission through ionic bombardment principle. The driving parameters to develop such a gun are to obtain a quite small electron gun for an in-flight instrument performing Electron Beam Fluorescence measurements (EBF) on board of a reentry vehicle in the upper atmosphere. These measurements are useful to characterize the gas flow around the vehicle in terms of gas chemical composition, temperatures and velocity of the flow which usually presents thermo-chemical non-equilibrium. Such an instrument can also be employed to characterize the upper atmosphere if placed on another carrier like a balloon. In ground facilities, it appears as a more practical tool to characterize flows in wind tunnel studies or as an alternative to complex electron guns in industrial processes requiring an electron beam. We describe in this paper the gun which has been developed as well as its different features which have been characterized in the laboratory.
The role of fast atom bombardment mass spectroscopy (FABMS) in cluster characterization
Sotelo, Adriana F.;Felicissimo, Anna Maria P.;
Química Nova , 2005, DOI: 10.1590/S0100-40422005000300007
Abstract: fast atom bombardment mass spectroscopy has been used to study a large number of cationic phosphine-containing transition-metal-gold clusters, which ranged in mass from 1000 to 4000. many of these clusters have been previously characterized and were examined in order to test the usefulness of the fabms technique. results showed that fabms is excellent in giving the correct molecular formula and when combined with nmr, ir, and microanalysis gave a reliable characterization for cationic clusters1. recently fabms has become one of the techniques employed as routine in cluster characterization2,3 and also is an effective tool for the structure analysis of large biomolecules4. some results in the present work reinforce the importance of these data in the characterization of clusters in the absence of crystals with quality for x-ray analysis.
Metal-insulator transition on SrTiO$_{3}$ surface induced by ionic-bombardment  [PDF]
Heiko Gross,Namrata Bansal,Yong-Seung Kim,Seongshik Oh
Physics , 2011, DOI: 10.1063/1.3650254
Abstract: SrTiO$_{3}$ is one of the most popular insulating single-crystal substrates for various complex-oxide thin film growths, because of its good lattice match with many complex oxide films. Here, we show that a common thin film processing technique, argon ion-milling, creates highly conducting layer on the surface of STO, not only at room temperatures but also at cryogenic temperatures at which thermal diffusion is completely suppressed. Systematic \emph{in situ} four-point conductance measurements were taken on single-crystal STO substrates inside vacuum environment. The evolution of metallicity out of insulating STO follows simple models based on oxygen vacancy doping effect. At cryogenic temperatures, ion milling created a thin - but much thicker than the argon-penetration depth - steady-state oxygen-vacant layer, leading to a highly-concentric metallic state. Near room temperatures, however, significant thermal diffusion occurred and the metallic state continuously diffused into the bulk, leaving only low concentraion of electron carriers on the surface. Analysis of the discrepancy between the experiments and the models also provided evidence for vacany clustering, which seems to occur during any vacancy formation process and affects the observed conductance. These observations suggest that the transport properties of films processed on STO substrates using energetic methods such as ion milling need to be taken with caution. On the other hand, if properly controlled, ionic bombardment could be used as a way to create selective conducting layers on the surface of STO for device applications.
A characterization of Inoue surfaces  [PDF]
Marco Brunella
Mathematics , 2010,
Abstract: We give a characterization of Inoue surfaces in terms of automorphic pluriharmonic functions on a cyclic covering. Together with results of Chiose and Toma, this completes the classification of compact complex surfaces of Kaehler rank one.
Insulator-to-metal transition of SrTiO3:Nb single crystal surfaces induced by Ar+ bombardment  [PDF]
C. Rodenbücher,S. Wicklein,R. Waser,K. Szot
Physics , 2013, DOI: 10.1063/1.4795611
Abstract: In this paper, the effect of Ar+ bombardment of SrTiO3:Nb surface layers is investigated on the macro- and nanoscale using surface-sensitive methods. After bombardment, the stoichiometry and electronic structure are changed distinctly leading to an insulator-to-metal transition related to the change of the Ti "d" electron from d0 to d1 and d2. During bombardment, conducting islands are formed on the surface. The induced metallic state is not stable and can be reversed due to a redox process by external oxidation and even by self-reoxidation upon heating the sample to temperatures of 300{\deg}C.
Experimental Characterization of Ionic Polymer Metal Composite as a Novel Fractional Order Element  [PDF]
Riccardo Caponetto,Salvatore Graziani,Fulvio L. Pappalardo,Francesca Sapuppo
Advances in Mathematical Physics , 2013, DOI: 10.1155/2013/953695
Abstract: Ionic polymer metal composites (IPMCs) are electroactive materials made of ionic polymer thin membranes with platinum metallization on their surfaces. They are interesting materials due to not only their electromechanical applications as transducers but also to their electrochemical features and the relationship between the ionic/solvent current and the potential field. Their electrochemical properties thus suggest the possibility for exploiting them as compact fractional-order elements (FOEs) with a view of defining fabrication processes and production strategies that assure the desired performances. In this paper, the experimental electrical characterization of a brand new IPMC setup in a fixed sandwich configuration is proposed. Two IPMC devices with different platinum absorption times (5?h and 20?h) are characterized through experimental data: first, a preliminary linearity study is performed for a fixed input voltage amplitude in order to determine the frequency region where IPMC can be approximated as linear; then, a frequency analysis is carried out in order to identify a coherent fractional-order dynamics in the bode diagrams. Such analyses take the first steps towards a simplified model of IPMC as a compact electronic FOE for which the fractional exponent value depends on fabrication parameters as the absorption time. 1. Introduction Ionic polymer-metal composites (IPMCs) as electroactive polymers (EAPs) have the very interesting capabilities of transforming electrical energy into mechanical energy, and vice versa [1, 2], making them privileged candidates for the realization of actuators or sensors with features as low required voltage, high compliance, lightness, softness, and so forth, thus, creating great interest in possible applications in very different fields such as robotics, aerospace, and biomedics [3–5]. They are composite materials made of ionic polymers in presence of solvent with layers of noble metals on their surfaces. Their structure and composition make their full exploitation currently limited because of the incomplete knowledge of their working principles and therefore a not clearly defined design procedure. Due to their electromechanical properties, they have been traditionally characterized as transducers, both as sensors and actuators, and three different strategies have been used to describe the relationship between the electrical and the mechanical behaviors [6]. The first one, referred to as black box and behavioral model, provides a purely empirical model of IPMCs obtained through a series of curve fits based on
Charge regulation and ionic screening of patchy surfaces  [PDF]
Niels Boon,René van Roij
Physics , 2010, DOI: 10.1063/1.3533279
Abstract: The properties of surfaces with charge-regulated patches are studied using non-linear Poisson-Boltzmann theory. Using a mode expansion to solve the non-linear problem efficiently, we reveal the charging behaviour of Debye-length sized patches. We find that patches charge up to higher charge densities if their size is relatively small and if the patches are well separated. The numerical results are used to construct a basic analytical model which predicts the average surface charge density on surfaces with patchy chargeable groups.
A characterization of spherical polyhedron surfaces  [PDF]
Feng Luo
Mathematics , 2004,
Abstract: A spherical polyhedron surface is a triangulated surface obtained by isometric gluing of spherical triangles. For instance, the boundary of a generic convex polytope in the 3-sphere is a spherical polyhedron surface. This paper investigates these surfaces from the point of view of inner angles. A rigidity result is obtained. A characterization of spherical polyhedron surfaces in terms of the triangulation and the angle assignment is established.
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