Migration of Au Nanoparticles on a TiO2(110) Surface in Reactant Gases Observed by In-Situ STM at Elevated Temperatures

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.

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The threshold energy for atom displacement in fcc metals

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100175788 ◽

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.

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In Situ Polymerized Protic Ionogels for Fuel Cells at Elevated Temperatures

Industrial & Engineering Chemistry Research ◽

10.1021/acs.iecr.0c04882 ◽

2021 ◽

Author(s):

Mengdou Zou ◽

Jie Luo ◽

Xurui Wang ◽

Shuai Tan ◽

Caihong Wang ◽

...

Keyword(s):

Fuel Cells ◽

Elevated Temperatures

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Three-Dimensional Atomic Structure of Supported Au Nanoparticles at High Temperature

Nanoscale ◽

10.1039/d0nr08664a ◽

2021 ◽

Author(s):

Pei Liu ◽

Ece Arslan Imran ◽

Annick De Backer ◽

Annelies de Wael ◽

Ivan Lobato ◽

...

Keyword(s):

High Temperature ◽

Atomic Structure ◽

Au Nanoparticles ◽

Elevated Temperatures ◽

Three Dimensional

Au nanoparticles (NPs) deposited on CeO2 are extensively used as thermal catalysts since the morphology of the NPs is expected to be stable at elevated temperatures. Although it is well...

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

Applied Spectroscopy ◽

10.1177/0003702821990445 ◽

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.

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In Situ Exsolved Au Nanoparticles from Perovskite Oxide for Efficient Epoxidation of Styrene

Journal of Materials Chemistry A ◽

10.1039/d1ta01203g ◽

2021 ◽

Author(s):

Yang Gao ◽

Xing Chen ◽

Shuqi Hu ◽

Shiguo Zhang

Keyword(s):

Density Functional Theory ◽

Thermodynamic Analysis ◽

Density Functional ◽

Au Nanoparticles ◽

Oxide Catalyst ◽

Density Functional Theory Calculations ◽

Average Diameter ◽

Perovskite Oxide ◽

Functional Theory

Au-doped SrTiO3 perovskite oxide catalyst (Sr0.995Au0.005TiO3-δ) has been designed and synthesized based on thermodynamic analysis and density functional theory calculations. During reduction, Au nanoparticles with an average diameter of 2...

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In-Situ XPS Monitoring and Characterization of Electrochemically Prepared Au Nanoparticles in an Ionic Liquid

ACS Omega ◽

10.1021/acsomega.6b00456 ◽

2017 ◽

Vol 2 (2) ◽

pp. 478-486 ◽

Cited By ~ 15

Author(s):

Merve T. Camci ◽

Burak Ulgut ◽

Coskun Kocabas ◽

Sefik Suzer

Keyword(s):

Ionic Liquid ◽

Au Nanoparticles ◽

In Situ Xps

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

MRS Proceedings ◽

10.1557/proc-318-13 ◽

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.

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