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Tsukasa Hirayama, Yuka Aizawa, Kazuo Yamamoto, Takeshi Sato, Hidekazu Murata, Ryuji Yoshida, Craig A J Fisher, Takehisa Kato, Yasutoshi Iriyama
Advanced techniques for overcoming problems encountered during in situ electron holography experiments in which a voltage is applied to an ionic conductor are reported. The three major problems encountered were 1) electric-field leakage from the specimen and its effect on phase images, 2) high electron conductivity of damage layers formed by the focused ion beam method, and 3) chemical reaction of the specimen with air. The first problem was overcome by comparing experimental phase distributions with simulated images in which three-dimensional leakage fields were taken into account, the second by removing the damage layers using a low-energy narrow Ar ion beam, and the third by developing an air-tight biasing specimen holder...
November 29, 2016: Ultramicroscopy
Y Tu, H Takamizawa, B Han, Y Shimizu, K Inoue, T Toyama, F Yano, A Nishida, Y Nagai
The relationship between the laser power and the three-dimensional distribution of boron (B) in silicon (Si) measured by laser-assisted atom probe tomography (APT) is investigated. The ultraviolet laser employed in this study has a fixed wavelength of 355nm. The measured distributions are almost uniform and homogeneous when using low laser power, while clear B accumulation at the low-index pole of single-crystalline Si and segregation along the grain boundaries in polycrystalline Si are observed when using high laser power (100pJ)...
November 25, 2016: Ultramicroscopy
Michael Stöger-Pollach, Lukáš Kachtík, Bernhard Miesenberger, Philipp Retzl
The excitation probability of transition radiation is measured for varying beam energies in a transmission electron microscope once using optical spectrometry of the emitted light and second using electron energy loss spectrometry. In both cases similar results are found being in good agreement with theory. The knowledge about this probability enables us to judge whether or not transition radiation has to be considered in EELS and CL data interpretation. Additionally it is shown that the emission of transition radiation happens at the sample surfaces only, when the electron passes the vacuum/sample interface and thus feeling the change of its dielectric environment...
November 23, 2016: Ultramicroscopy
Juri Barthel, Markus Lentzen, Andreas Thust
We investigate a possible dependence between the applied electron dose-rate and the magnitude of the resulting image contrast in HRTEM of inorganic crystalline objects. The present study is focussed on the question whether electron irradiation can induce excessively strong atom vibrations or displacements, which in turn could significantly reduce the resulting image contrast. For this purpose, high-resolution images of MgO, Ge, and Au samples were acquired with varying dose rates using a CS-corrected FEI Titan 80-300 microscope operated at 300kV accelerating voltage...
November 22, 2016: Ultramicroscopy
Michael Stöger-Pollach, Thomas Schachinger, Kati Biedermann, Volkhard Beyer
In this experimental work we present novel methods to increase the spatial resolution of valence electron energy loss spectrometry (VEELS) investigations below the limit given by the inelastic delocalization. For this purpose we analyse a layer stack consisting of silicon/silicon-oxide/silicon-nitride/silicon-oxide/silicon (SONOS) with varying layer thickness down to the 2nm level. Using a combination of a conical illumination and energy filtered transmission electron microscopy we are able to identify the layers by using low energy losses...
November 22, 2016: Ultramicroscopy
T Maeda, K Kaneko, K Yamada, A Roy, Y Sato, R Teranishi, T Kato, T Izumi, Y Shiohara
In the context of high temperature superconductors, pulsed laser deposition derived GdBa2Cu3O7-δ sample with BaHfO3 nanoparticles has been reported to achieve high current density and good IC-B-θ characteristics at high temperatures. Herein, we have carried out a thorough nanostrucural characterization of BaHfO3 nanoparticles embedded in GdBCO matrix using scanning transmission electron microscopy, with an emphasis on the dispersion behavior, morphologies and nanostrain, to understand the role of BaHfO3 nanoparticles...
November 22, 2016: Ultramicroscopy
M G Burke, G Bertali, E Prestat, F Scenini, S J Haigh
In situ analytical transmission electron microscopy (TEM) can provide a unique perspective on dynamic reactions in a variety of environments, including liquids and gases. In this study, in situ analytical TEM techniques have been applied to examine the localised oxidation reactions that occur in a Ni-Cr-Fe alloy, Alloy 600, using a gas environmental cell at elevated temperatures. The initial stages of preferential intergranular oxidation, shown to be an important precursor phenomenon for intergranular stress corrosion cracking in pressurized water reactors (PWRs), have been successfully identified using the in situ approach...
November 21, 2016: Ultramicroscopy
Olof Bäcke, Camilla Lindqvist, Amaia Diaz de Zerio Mendaza, Stefan Gustafsson, Ergang Wang, Mats R Andersson, Christian Müller, Per Magnus Kristiansen, Eva Olsson
We show by in situ microscopy that the effects of electron beam irradiation during transmission electron microscopy can be used to lock microstructural features and enhance the structural thermal stability of a nanostructured polymer:fullerene blend. Polymer:fullerene bulk-heterojunction thin films show great promise for use as active layers in organic solar cells but their low thermal stability is a hindrance. Lack of thermal stability complicates manufacturing and influences the lifetime of devices. To investigate how electron irradiation affects the thermal stability of polymer:fullerene films, a model bulk-heterojunction film based on a thiophene-quinoxaline copolymer and a fullerene derivative was heat-treated in-situ in a transmission electron microscope...
November 21, 2016: Ultramicroscopy
Ana Okariz, Teresa Guraya, Maider Iturrondobeitia, Julen Ibarretxe
The SIRT (Simultaneous Iterative Reconstruction Technique) algorithm is commonly used in Electron Tomography to calculate the original volume of the sample from noisy images, but the results provided by this iterative procedure are strongly dependent on the specific implementation of the algorithm, as well as on the number of iterations employed for the reconstruction. In this work, a methodology for selecting the iteration number of the SIRT reconstruction that provides the most accurate segmentation is proposed...
November 19, 2016: Ultramicroscopy
Xing Meng
Estimation was made for visibility of phase contrast with varying extraction voltages. The resulting decay rates of visibility show that images with low image contrast from cryo EM will be seriously impacted with high extraction voltages.
November 19, 2016: Ultramicroscopy
Agnieszka Priebe, Guillaume Audoit, Jean-Paul Barnes
We present a novel sample preparation method that allows correlative 3D X-ray Computed Nano-Tomography (CNT) and Focused Ion Beam Time-Of-Flight Secondary Ion Mass Spectrometry (FIB-TOF-SIMS) tomography to be performed on the same sample. In addition, our invention ensures that samples stay unmodified structurally and chemically between the subsequent experiments. The main principle is based on modifying the topography of the X-ray CNT experimental setup before FIB-TOF-SIMS measurements by incorporating a square washer around the sample...
November 19, 2016: Ultramicroscopy
Matthew J Burch, Chris M Fancher, Srikanth Patala, Marc De Graef, Elizabeth C Dickey
A novel technique, which directly and nondestructively maps polar domains using electron backscatter diffraction (EBSD) is described and demonstrated. Through dynamical diffraction simulations and quantitative comparison to experimental EBSD patterns, the absolute orientation of a non-centrosymmetric crystal can be determined. With this information, the polar domains of a material can be mapped. The technique is demonstrated by mapping the non-ferroelastic, or 180°, ferroelectric domains in periodically poled LiNbO3 single crystals...
November 18, 2016: Ultramicroscopy
Juliane Reinhardt, Robert Hoppe, Georg Hofmann, Christian D Damsgaard, Jens Patommel, Christoph Baumbach, Sina Baier, Amélie Rochet, Jan-Dierk Grunwaldt, Gerald Falkenberg, Christian G Schroer
In recent years, X-ray ptychography has been established as a valuable tool for high-resolution imaging. Nevertheless, the spatial resolution and sensitivity in coherent diffraction imaging are limited by the signal that is detected over noise and over background scattering. Especially, coherent imaging of weakly scattering specimens suffers from incoherent background that is generated by the interaction of the central beam with matter along its propagation path in particular close to and inside of the detector...
November 14, 2016: Ultramicroscopy
Wolfgang Wisniewski, Stefan Saager, Andrea Böbenroth, Christian Rüssel
Experiments concerning the information depth of electron backscatter diffraction (EBSD) are performed on samples featuring an amorphous wedge on a crystalline substrate and a crystalline wedge on an amorphous substrate. The effects of the acceleration voltage and exemplary software settings on the ability to measure through an amorphous layer are presented. Changes in the EBSD-signal could be detected through a ≈142nm thick layer of amorphous Si while orientation measurements could be performed through a ≈116nm thick layer when using a voltage of 30kV...
November 12, 2016: Ultramicroscopy
B Winiarski, A Gholinia, K Mingard, M Gee, G E Thompson, P J Withers
Here we examine the potential of serial Broad Ion Beam (BIB) Ar(+) ion polishing as an advanced serial section tomography (SST) technique for destructive 3D material characterisation for collecting data from volumes with lateral dimensions significantly greater than 100µm and potentially over millimetre sized areas. Further, the associated low level of damage introduced makes BIB milling very well suited to 3D EBSD acquisition with very high indexing rates. Block face serial sectioning data registration schemes usually assume that the data comprises a series of parallel, planar slices...
November 11, 2016: Ultramicroscopy
A P Gregory, J F Blackburn, T E Hodgetts, R N Clarke, K Lees, S Plint, G A Dimitrakis
This paper describes traceable measurements of the dielectric permittivity and loss tangent of a multiphase material (particulate rock set in epoxy) at micron scales using a resonant Near-Field Scanning Microwave Microscope (NSMM) at 1.2GHz. Calibration and extraction of the permittivity and loss tangent is via an image charge analysis which has been modified by the use of the complex frequency to make it applicable for high loss materials. The results presented are obtained using a spherical probe tip, 0.1mm in diameter, and also a conical probe tip with a rounded end 0...
November 5, 2016: Ultramicroscopy
Katja Berlin, Achim Trampert
Melting and crystallization dynamics of the multi-component Ge-Sb-Te alloy have been investigated by in-situ transmission electron microscopy (TEM). Starting point of the phase transition study is an ordered hexagonal Ge1Sb2Te4 thin film on Si(111) where the crystal structure and the chemical composition are verified by scanning TEM and electron energy-loss spectroscopy, respectively. The in-situ observation of the liquid phase at 600°C including the liquid-solid and liquid-vacuum interfaces and their movements was made possible due to an encapsulation of the TEM sample...
November 5, 2016: Ultramicroscopy
Simon Martin, Nicolas Baboux, David Albertini, Brice Gautier
In this paper, we propose a thorough experimental procedure to assess the ferroelectricity of thin films, and apply this procedure to Pulsed Laser Deposition grown GaFeO3 thin films at the macroscale by means of Polarisation-Voltage hysteresis and at the nanoscale by Piezoresponse Force Microscopy. GaFeO3 is a serious candidate for the multiferroicity at room temperature, being ferrimagnetic and possibly ferroelectric. However, the non-ambiguous measurement of ferroelectric polarisation of such thin films remains a challenge...
November 3, 2016: Ultramicroscopy
Z Chen, D J Taplin, M Weyland, L J Allen, S D Findlay
The increasing use of energy dispersive X-ray spectroscopy in atomic resolution scanning transmission electron microscopy invites the question of whether its success in precision composition determination at lower magnifications can be replicated in the atomic resolution regime. In this paper, we explore, through simulation, the prospects for composition measurement via the model system of AlxGa1-xAs, discussing the approximations used in the modelling, the variability in the signal due to changes in configuration at constant composition, and the ability to distinguish between different compositions...
October 21, 2016: Ultramicroscopy
Tomohiro Miyata, Teruyasu Mizoguchi
Investigation of the local structure, ionic and molecular behavior, and chemical reactions at high spatial resolutions in liquids has become increasingly important. Improvements in these areas help to develop efficient batteries and improve organic syntheses. Transmission electron microscopy (TEM) and scanning-TEM (STEM) have excellent spatial resolution, and the electron energy-loss near edge structure (ELNES) measured by the accompanied electron energy-loss spectroscopy (EELS) is effective to analyze the liquid local structure owing to reflecting the electronic density of states...
October 19, 2016: Ultramicroscopy
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