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End date: 2020 × Start date: 2020 × DDC: 530 × DDC: 540 × Type: Article × WGL Institute: IOM ×

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Now showing 1 - 3 of 3
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    An investigation on effectiveness of temperature treatment for fluorine-based reactive plasma jet machining of N-BK7®
    (Hoboken, NJ : Wiley Interscience, 2020) Kazemi, Faezeh; Boehm, Georg; Arnold, Thomas
    In this study, a fluorine-based reactive plasma jet is investigated as a promising tool for ultraprecise surface machining of N-BK7®. Plasma-generated particles react with an N-BK7 surface to create volatile and nonvolatile compounds. The desorption of volatile compounds results in an etched surface, whereas nonvolatile compounds form a residual layer in the etched area, causing unpredictable effects on the etching rate. Surface temperature treatment is proposed to improve the machining procedure with respect to deterministic material removal, leading to predictable results. It is shown that, at an elevated surface temperature, the residual layer properties are modified in favor of improved etching performance. The etching behavior of N-BK7 is compared with fused silica to verify the optimality of the obtained results.
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    Antiphase Boundaries Constitute Fast Cation Diffusion Paths in SrTiO3 Memristive Devices
    (Weinheim : Wiley-VCH, 2020) Heisig, Thomas; Kler, Joe; Du, Hongchu; Baeumer, Christoph; Hensling, Felix; Glöß, Maria; Moors, Marco; Locatelli, Andrea; Menteş, Tevfik Onur; Genuzio, Francesca; Mayer, Joachim; De Souza, Roger A.; Dittmann, Regina
    Resistive switching in transition metal oxide-based metal-insulator-metal structures relies on the reversible drift of ions under an applied electric field on the nanoscale. In such structures, the formation of conductive filaments is believed to be induced by the electric-field driven migration of oxygen anions, while the cation sublattice is often considered to be inactive. This simple mechanistic picture of the switching process is incomplete as both oxygen anions and metal cations have been previously identified as mobile species under device operation. Here, spectromicroscopic techniques combined with atomistic simulations to elucidate the diffusion and drift processes that take place in the resistive switching model material SrTiO3 are used. It is demonstrated that the conductive filament in epitaxial SrTiO3 devices is not homogenous but exhibits a complex microstructure. Specifically, the filament consists of a conductive Ti3+-rich region and insulating Sr-rich islands. Transmission electron microscopy shows that the Sr-rich islands emerge above Ruddlesden–Popper type antiphase boundaries. The role of these extended defects is clarified by molecular static and molecular dynamic simulations, which reveal that the Ruddlesden–Popper antiphase boundaries constitute diffusion fast-paths for Sr cations in the perovskites structure. © 2020 The Authors. Published by Wiley-VCH GmbH
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    Orientation‐dependent nanostructuring of titanium surfaces by low‐energy ion beam erosion
    (Chichester [u.a.] : Wiley, 2020) Bauer, Jens; Frost, Frank
    Regular nanoscopic ripple and dot patterns are fabricated on poly-crystalline titanium samples by irradiation with 1.5 keV argon ions at normal incidence. The morphology of the nanostructures is investigated by scanning electron microscopy and scanning force microscopy. The ripple structures exhibit a saw-tooth cross-section profile. Electron backscatter diffraction experiments are performed to analyze the local grain structure. The study suggests a distinct correlation of the nanostructure morphology to the crystallographic orientation of the titanium surface.