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13 results on '"Peter van Aken"'

1. High-temperature-grown buffer layer boosts electron mobility in epitaxial La-doped BaSnO3/SrZrO3 heterostructures

Author

Arnaud P. Nono Tchiomo, Wolfgang Braun, Bryan P. Doyle, Wilfried Sigle, Peter van Aken, Jochen Mannhart, and Prosper Ngabonziza

Subjects
Biotechnology, TP248.13-248.65, Physics, QC1-999
Abstract

By inserting a SrZrO3 buffer layer between the film and the substrate, we demonstrate a significant reduction of the threading dislocation density with an associated improvement of the electron mobility in La:BaSnO3 films. A room temperature mobility of 140 cm2 V−1s−1 is achieved for 25-nm-thick films without any postgrowth treatment. The density of threading dislocations is only 4.9 × 109 cm−2 for buffered films prepared on (110) TbScO3 substrates by pulsed laser deposition.

Published
2019
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2. Numerical simulations of interference effects in photon-assisted electron energy-loss spectroscopy

Author

Nahid Talebi, Wilfried Sigle, Ralf Vogelgesang, and Peter van Aken

Subjects
Science, Physics, QC1-999
Abstract

Although the electromagnetic resonances of individual nanostructures can be studied by electron or photon interactions alone, exciting new possibilities open up through the simultaneous use of both. In photon-induced near-field electron microscopy (PINEM), for example, single nanostructures are optically excited by short, intense pulses and concurrently imaged with high spatial resolution by fast electrons, which act as negligible probes of electric fields. Controlling their relative arrival time provides access to the dynamics of the electromagnetic response in the near field by recording images of the electron energy loss (or gain) spectra. In this paper, we investigate the transition from optically dominated PINEM to conventional, electron-dominated electron energy-loss spectroscopy (EELS). During the systematic reduction of optical excitation intensity to zero, a novel electro-optical interference effect emerges. It reveals itself at those optical field strengths that lead to prominently visible constructive and destructive interference patterns of the optical and electron radiation fields which are scattered by a nanostructure. The interference patterns reported here allow one to achieve higher temporal, energy and spatial resolutions of the modal dynamics in electron microscopy.

Published
2013
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3. Fermi energy, electrical conductivity, and the energy gap of NaNbO3

Author

Nicole Bein, Brigita Kmet, Tadej Rojac, Andreja Benčan Golob, Barbara Malič, Julian Moxter, Thorsten Schneider, Lovro Fulanovic, Maryam Azadeh, Till Frömling, Sonja Egert, Hongguang Wang, Peter van Aken, Jutta Schwarzkopf, and Andreas Klein

Subjects
Physics and Astronomy (miscellaneous), General Materials Science
Published
2022
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4. Gradient-flipping-assisted Flux-preserving Wave Reconstruction for Improved Lowspatial- Frequency Recovery and High-contrast Imaging Using in-line Holography

Author

Cigdem Ozsoy Keskinbora, Wouter Van den Broek, Chris Boothroyd, Rafal Dunin-Borkowski, Peter van Aken, and Christoph Koch

Abstract

In-line holography in the transmission electron microscope is a versatile technique, which provides real-space phase information that can be used for the correction of imaging aberrations, as well as for measuring electric and magnetic fields and strain distributions. It is able to recover high-spatial-frequency contributions to the phase effectively but suffers from the weak transfer of low-spatial-frequency information, as well as from incoherent scattering. Here, we combine gradient flipping and phase prediction in an iterative flux-preserving focal series reconstruction algorithm with incoherent background subtraction that gives extensive access to the missing low spatial frequencies. A procedure for optimizing the reconstruction parameters is presented, and results from MgO cubes, and Fe-filled C nanospheres are compared with phase images obtained using off-axis holography.

Published
2022
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10. Applying Structure and Discipline to Rig Technology

Author

Peter Van Aken, Pat Slagle, and Cris DeWitt

Subjects
Engineering, Quality management, Software, business.industry, Control system, Computer software, Complex system, Software system, Overall performance, business, Manufacturing engineering, Simulation, Coding (social sciences)
Abstract

The maritime and offshore industries are increasingly reliant on integrated computer-based control systems and the associated software that actually ‘runs’ the systems. Industrial computers and the software they run are controlling exponentially more rig functions than ever before with increasingly more complex coding for expanded functionality. Ultimately, introduction of these complex systems into safety, environmental and operational functions have a significant impact on rig performance—software quality management is becoming a primary contributor to the overall performance of a rig.

Published
2012
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11. The heterogeneous composition of working place aerosols in a nickel refinery: a transmission and scanning electron microscope study

Author

Stephan, Weinbruch, Peter, van Aken, Martin, Ebert, Yngvar, Thomassen, Asbjørn, Skogstad, Valery P, Chashchin, and Alexander, Nikonov

Subjects
Aerosols, Microscopy, Electron, Nickel, Air Pollution, Indoor, Metallurgy, Microscopy, Electron, Scanning, Particle Size, Workplace, Environmental Monitoring
Abstract

Size, morphology and chemical composition of individual aerosol particles collected in a nickel refinery were analyzed by scanning electron microscopy and energy-dispersive X-ray microanalysis (EDX). The phase composition was determined by selected area electron diffraction and EDX in a transmission electron microscope. Most particles are heterogeneous on a nanometer scale and consist of various phases. Nickel phases observed in the roasting and anode casting departments include metallic nickel, bunsenite (NiO), trevorite (Ni,Cu)Fe2O4, heazlewoodite Ni3S2, godlevskite (Ni,Cu)9S8, orthorhombic NiSO4 and an amorphous Ni,Cu.Al,Pb sulfate of variable composition. Additional phases encountered include corundum (Al2O3), murdochite (PbCu6O8), hexagonal Na2SO4, anhydrite (CaSO4), graphite (C) and amorphous carbon. The implications of the occurrence of the different Ni phases and their nanometer size for the study of adverse health effects are explored.

Published
2002

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