Device Characteristics of In Situ CCVD Grown Bilayer Graphene FETs at Elevated Temperatures

2012 ◽  
Vol 45 (4) ◽  
pp. 23-30
Author(s):  
P. J. Wessely ◽  
F. Wessely ◽  
E. Birinci ◽  
B. Riedinger ◽  
U. Schwalke
Keyword(s):  
Elevated Temperatures ◽  
Bilayer Graphene

Electron and ion irradiation-induced dissolution of mechanical twins in the intermetalic U3Si: An in situ HVEM study

1989 ◽  
Vol 47 ◽  
pp. 652-653
Author(s):  
Charles W. Allen ◽  
Robert C. Birtcher
Keyword(s):  
Elevated Temperatures ◽  
Ion Irradiation ◽  
Ion Beam ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Heavy Ion ◽  
High Energy ◽  
Mechanical Twinning ◽  
In Situ Experiments

The uranium silicides, including U3Si, are under study as candidate low enrichment nuclear fuels. Ion beam simulations of the in-reactor behavior of such materials are performed because a similar damage structure can be produced in hours by energetic heavy ions which requires years in actual reactor tests. This contribution treats one aspect of the microstructural behavior of U3Si under high energy electron irradiation and low dose energetic heavy ion irradiation and is based on in situ experiments, performed at the HVEM-Tandem User Facility at Argonne National Laboratory. This Facility interfaces a 2 MV Tandem ion accelerator and a 0.6 MV ion implanter to a 1.2 MeV AEI high voltage electron microscope, which allows a wide variety of in situ ion beam experiments to be performed with simultaneous irradiation and electron microscopy or diffraction.At elevated temperatures, U3Si exhibits the ordered AuCu3 structure. On cooling below 1058 K, the intermetallic transforms, evidently martensitically, to a body-centered tetragonal structure (alternatively, the structure may be described as face-centered tetragonal, which would be fcc except for a 1 pet tetragonal distortion). Mechanical twinning accompanies the transformation; however, diferences between electron diffraction patterns from twinned and non-twinned martensite plates could not be distinguished.

The threshold energy for atom displacement in fcc metals

1990 ◽  
Vol 48 (4) ◽  
pp. 530-531
Author(s):  
Wilfried Sigle ◽  
Matthias Hohenstein ◽  
Alfred Seeger
Keyword(s):  
Growth Rate ◽  
Elevated Temperatures ◽  
Threshold Energy ◽  
Dislocation Loops ◽  
Absolute Minimum ◽  
Voltage Electron ◽  
Atom Displacement ◽  
Electron Microscopes ◽  
Fcc Metal

Prolonged electron irradiation of metals at elevated temperatures usually leads to the formation of large interstitial-type dislocation loops. The growth rate of the loops is proportional to the total cross-section for atom displacement,which is implicitly connected with the threshold energy for atom displacement, Ed . Thus, by measuring the growth rate as a function of the electron energy and the orientation of the specimen with respect to the electron beam, the anisotropy of Ed can be determined rather precisely. We have performed such experiments in situ in high-voltage electron microscopes on Ag and Au at 473K as a function of the orientation and on Au as a function of temperature at several fixed orientations.Whereas in Ag minima of Ed are found close to <100>,<110>, and <210> (13-18eV), (Fig.1) atom displacement in Au requires least energy along <100>(15-19eV) (Fig.2). Au is thus the first fcc metal in which the absolute minimum of the threshold energy has been established not to lie in or close to the <110> direction.

In Situ Polymerized Protic Ionogels for Fuel Cells at Elevated Temperatures

2021 ◽  
Author(s):  
Mengdou Zou ◽  
Jie Luo ◽  
Xurui Wang ◽  
Shuai Tan ◽  
Caihong Wang ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Elevated Temperatures

scholarly journals Ultraviolet Absorption Cross-Sections of Ammonia at Elevated Temperatures for Nonintrusive Quantitative Detection in Combustion Environments

2021 ◽  
pp. 000370282199044
Author(s):  
Wubin Weng ◽  
Shen Li ◽  
Marcus Aldén ◽  
Zhongshan Li
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Absorption Cross Section ◽  
Elevated Temperatures ◽  
Uv Absorption ◽  
Energy Utilization ◽  
Quantitative Detection ◽  
Absorption Cross ◽  
Hot Gas

Ammonia (NH3) is regarded as an important nitrogen oxides (NOx) precursor and also as an effective reductant for NOx removal in energy utilization through combustion, and it has recently become an attractive non-carbon alternative fuel. To have a better understanding of thermochemical properties of NH3, accurate in situ detection of NH3 in high temperature environments is desirable. Ultraviolet (UV) absorption spectroscopy is a feasible technique. To achieve quantitative measurements, spectrally resolved UV absorption cross-sections of NH3 in hot gas environments at different temperatures from 295 K to 590 K were experimentally measured for the first time. Based on the experimental results, vibrational constants of NH3 were determined and used for the calculation of the absorption cross-section of NH3 at high temperatures above 590 K using the PGOPHER software. The investigated UV spectra covered the range of wavelengths from 190 nm to 230 nm, where spectral structures of the [Formula: see text] transition of NH3 in the umbrella bending mode, v2, were recognized. The absorption cross-section was found to decrease at higher temperatures. For example, the absorption cross-section peak of the (6, 0) vibrational band of NH3 decreases from ∼2 × 10−17 to ∼0.5 × 10−17 cm2/molecule with the increase of temperature from 295 K to 1570 K. Using the obtained absorption cross-section, in situ nonintrusive quantification of NH3 in different hot gas environments was achieved with a detection limit varying from below 10 parts per million (ppm) to around 200 ppm as temperature increased from 295 K to 1570 K. The quantitative measurement was applied to an experimental investigation of NH3 combustion process. The concentrations of NH3 and nitric oxide (NO) in the post flame zone of NH3–methane (CH4)–air premixed flames at different equivalence ratios were measured.

In-Situ Characterization of Growth and Intermixing at a Heteroepitaxial Interface: Fe on Au(001)

1993 ◽  
Vol 318 ◽  
Author(s):  
Q. Jiang ◽  
A. Chan ◽  
Y.-L. He ◽  
G.-C. Wang
Keyword(s):  
Elevated Temperatures ◽  
Chemical Elements ◽  
Background Intensity ◽  
In Situ Characterization ◽  
Initial Stage ◽  
Monolayer Growth ◽  
Low Energy Electron ◽  
Energy Dependent

ABSTRACTThe growth and chemical intermixing of submonolayer and a few monolayer thick Fe films on a Au(001) surface was studied by High Resolution Low Energy Electron Diffraction (HRLEED) technique. Through the analysis of the energy dependent angular profiles as a function of time, we obtained the distribution of islands and distribution of spacings during submonolayer growth. The interference of electron waves from different chemical elements in terraces at different heights in the surface contributes to the background intensity and broadening in the angular profiles of diffraction beams. A subsurface Fe capped by Au islands as a result of atomic place exchange was observed at the initial stage of monolayer growth. From the energy dependent angular profiles as a function of temperature, we determine the quantitative change of inhomogeneity length (∼20 Å) at the interface of ultrathin films at elevated temperatures due to intermixing.

An in situ microtomography apparatus with a laboratory x-ray source for elevated temperatures of up to 1000 °C

2021 ◽  
Vol 92 (3) ◽  
pp. 033704
Author(s):  
Rongqi Zhu ◽  
Zhaoliang Qu ◽  
Shuo Yang ◽  
Daining Fang
Keyword(s):  
Elevated Temperatures ◽  
X Ray

Pressure and Temperature Adaptation of Cytosolic Malate Dehydrogenases of Shallowand Deep-Living Marine Invertebrates: Evidence for High Body Temperatures in Hydrothermal Vent Animals

1991 ◽  
Vol 159 (1) ◽  
pp. 473-487 ◽  
Author(s):  
ELIZABETH DAHLHOFF ◽  
GEORGE N. SOMERO
Keyword(s):  
Deep Sea ◽  
Hydrothermal Vents ◽  
Elevated Temperatures ◽  
Marine Invertebrates ◽  
Distribution Patterns ◽  
Pressure Effects ◽  
Temperature Adaptation ◽  
Body Temperatures ◽  
Elevated Pressures

Effects of temperature and hydrostatic pressure were measured on cytosolic malate dehydrogenases (cMDHs) from muscle tissue of a variety of shallow- and deep-living benthic marine invertebrates, including seven species endemic to the deep-sea hydrothermal vents. The apparent Michaelis-Menten constant (Km) of coenzyme (nicotinamide adenine dinucleotide, NADH), used to index temperature and pressure effects, was conserved within a narrow range (approximately 15–25 μmoll−1) at physiological temperatures and pressures for all species. However, at elevated pressures, the Km of NADH rose sharply for cMDHs of shallow species (depths of occurrence &gt;Approximately 500 m), but not for the cMDHs of deep-sea species. Cytosolic MDHs of invertebrates from the deep-sea hydrothermal vents generally were not perturbed by elevated temperatures (15–25°C) at in situ pressures, but cMDHs of cold-adapted deep-sea species were. At a single measurement temperature, the Km of NADH for cMDHs from invertebrates from habitats with well-characterized temperatures was inversely related to maximal sustained body temperature. This correlation was used to predict the maximal sustained body temperatures of vent invertebrates for which maximal habitat and body temperatures are difficult to estimate. Species occurring on the ‘smoker chimneys’, which emit waters with temperatures up to 380°C, are predicted to have sustained body temperatures that are approximately 20–25°C higher than vent species living in cooler vent microhabitats. We conclude that, just as adaptation of enzymes to elevated pressures is important in establishing species’ depth distribution patterns, adaptation of pressure-adapted enzymes to temperature is critical in enabling certain vent species to exploit warm-water microhabitats in the vent environment.

scholarly journals Extremely flat band in bilayer graphene

2018 ◽  
Vol 4 (11) ◽  
pp. eaau0059 ◽  
Author(s):  
D. Marchenko ◽  
D. V. Evtushinsky ◽  
E. Golias ◽  
A. Varykhalov ◽  
Th. Seyller ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
Bilayer Graphene ◽  
Flat Band ◽  
Honeycomb Lattice ◽  
Band Model ◽  
Two Dimensional ◽  
Band Formation ◽  
Constant Energy ◽  
Mexican Hat ◽  
Band Dispersion

We propose a novel mechanism of flat band formation based on the relative biasing of only one sublattice against other sublattices in a honeycomb lattice bilayer. The mechanism allows modification of the band dispersion from parabolic to “Mexican hat”–like through the formation of a flattened band. The mechanism is well applicable for bilayer graphene—both doped and undoped. By angle-resolved photoemission from bilayer graphene on SiC, we demonstrate the possibility of realizing this extremely flattened band (< 2-meV dispersion), which extends two-dimensionally in a k-space area around the K¯ point and results in a disk-like constant energy cut. We argue that our two-dimensional flat band model and the experimental results have the potential to contribute to achieving superconductivity of graphene- or graphite-based systems at elevated temperatures.

Investigation of Pt Bottom Electrodes for "In-Situ" Deposited Pb(Zr,Ti)O3 (PZT) thin Films

1991 ◽  
Vol 243 ◽  
Author(s):  
Rainer Bruchhaus ◽  
Dana Pitzer ◽  
Oliver Eibl ◽  
Uwe Scheithauer ◽  
Wolfgang Hoesler
Keyword(s):  
Elevated Temperatures ◽  
Diffusion Processes ◽  
Rutherford Backscattering Spectrometry ◽  
Layer Sequence ◽  
Si Substrates ◽  
Transmission Electron ◽  
In Situ Deposition ◽  
Electron Spectrometry ◽  
Heating Up

AbstractThe deposition of the bottom electrode plays a key role in the fabrication of ferroelectric capacitors. Processing at elevated temperatures of up to 800°C can give rise to diffusion processes and thereof formation of harmful dielectric layers.In this paper we used Rutherford backscattering spectrometry (RBS), Auger electron spectrometry (AES) and transmission electron microscopy (TEM) to study Pt/Ti/SiO2/Si substrates with various thicknesses of the Ti and Pt layers. During heating up to about 450°C in vacuum the initial layer sequence remains unchanged. However, drastic changes occur when the electrodes are exposed to Ar/O2 atmosphere during heat treatment. Oxidation induced diffusion of Ti into Pt and oxidation of Ti were observed. A Pt electrode with a 100 nm thick Ti adhesion layer proved to be suitable for the "in-situ" deposition of PZT films.

In situ investigation of distortion of multilayer structures at elevated temperatures

1988 ◽  
Vol 33 (3) ◽  
pp. 871-874 ◽  
Author(s):  
G. Leitner ◽  
H. Balke ◽  
F. Schuster ◽  
I. Storbeck ◽  
M. Wolf
Keyword(s):  
Elevated Temperatures ◽  
Multilayer Structures ◽  
In Situ Investigation
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