Direct quantification of surface barriers for mass transfer in nanoporous crystalline materials

The mass transfer during the initial etching process: Si atoms dissolve in the Au film, and then diffuse across the Au lattice, and are oxidized and etched away at the Au film/solution interface.

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Control of Surface Barriers in Mass Transfer to Modulate Methanol‐to‐Olefins Reaction over SAPO‐34 Zeolites

Angewandte Chemie International Edition ◽

10.1002/anie.202009230 ◽

2020 ◽

Vol 59 (49) ◽

pp. 21945-21948

Author(s):

Shichao Peng ◽

Mingbin Gao ◽

Hua Li ◽

Miao Yang ◽

Mao Ye ◽

...

Keyword(s):

Mass Transfer ◽

Surface Barriers

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Self- concentrated mass-transfer during deformation treatments of organic-inorganic compositions

Journal of Physics Conference Series ◽

10.1088/1742-6596/2056/1/012039 ◽

2021 ◽

Vol 2056 (1) ◽

pp. 012039

Author(s):

I S Tsebruk ◽

A P Pokidov ◽

V V Kedrov ◽

N V Klassen

Keyword(s):

Mass Transfer ◽

Chemical Interaction ◽

Cesium Iodide ◽

Main Process ◽

Concentrated Mass ◽

Effective Utilization ◽

Crystalline Materials ◽

Ball Rolling ◽

The Matrix ◽

Deformation Treatment

Abstract This paper prolongs the series of our previous papers where we found super-fast and super-deep introduction of foreign substances in crystalline materials by means of the ball rolling. A set of new experimental results was used to justify the new version of the mechanism of this introduction with the record speed and depth. The main process which determines this phenomena is connected with the sequence of openings and closings of nanocracks at the surface subjected to the rolling and the capture of the substance introduced from the surface by these cracks. The process of this introduction with the record parameters is supported by the intense chemical interactions between the matrix and the substance being introduced. This chemical interaction is intensified by several times with the deformation treatments. The analogous super-fast mass transfer is observed in the situation of the pulling out of the polystyrene fibers from the solution of polystyrene in benzene when the interaction of the organic components with cesium iodide nanoparticles was activated by the deformation treatment of the solution during its pulling out resulting in the formation of big amounts of nano-channels promising for effective utilization of hazardous radioactive wastes.

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Resolution, Contrast and Interpretation of HVEM Images of Crystals

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100071582 ◽

1973 ◽

Vol 31 ◽

pp. 228-229

Author(s):

L. E. Thomas ◽

J. S. Lally ◽

R. M. Fisher

Keyword(s):

High Voltage ◽

Chromatic Aberration ◽

Crystalline Materials ◽

Resolution Parameter ◽

Instrument Resolution ◽

Imaging Conditions ◽

Beam Excitation ◽

Optimum Imaging

In addition to improved penetration at high voltage, the characteristics of HVEM images of crystalline materials are changed markedly as a result of many-beam excitation effects. This leads to changes in optimum imaging conditions for dislocations, planar faults, precipitates and other features.Resolution - Because of longer focal lengths and correspondingly larger aberrations, the usual instrument resolution parameter, CS174 λ 374 changes by only a factor of 2 from 100 kV to 1 MV. Since 90% of this change occurs below 500 kV any improvement in “classical” resolution in the MVEM is insignificant. However, as is widely recognized, an improvement in resolution for “thick” specimens (i.e. more than 1000 Å) due to reduced chromatic aberration is very large.

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TEM studies of amorphization processes and amorphous structures

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100104303 ◽

1988 ◽

Vol 46 ◽

pp. 448-449

Author(s):

T. E. Mitchell ◽

R. B. Schwarz

Keyword(s):

Amorphous Materials ◽

Fission Products ◽

Rapid Quenching ◽

Surface Films ◽

List Type ◽

Oxide Glasses ◽

Crystalline Materials ◽

Amorphous Structures ◽

Amorphous Surface ◽

Interfacial Films

Traditional oxide glasses occur naturally as obsidian and can be made easily by suitable cooling histories. In the past 30 years, a variety of techniques have been discovered which amorphize normally crystalline materials such as metals. These include [1-3]:Rapid quenching from the vapor phase.Rapid quenching from the liquid phase.Electrodeposition of certain alloys, e.g. Fe-P.Oxidation of crystals to produce amorphous surface oxide layers.Interdiffusion of two pure crystalline metals.Hydrogen-induced vitrification of an intermetal1ic.Mechanical alloying and ball-milling of intermetal lie compounds.Irradiation processes of all kinds using ions, electrons, neutrons, and fission products.We offer here some general comments on the use of TEM to study these materials and give some particular examples of such studies.Thin specimens can be prepared from bulk homogeneous materials in the usual way. Most often, however, amorphous materials are in the form of surface films or interfacial films with different chemistry from the substrates.

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Possible applications of fraunhofer holography in high resolution electron microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100108258 ◽

1978 ◽

Vol 36 (1) ◽

pp. 222-223 ◽

Cited By ~ 1

Author(s):

N. Bonnet ◽

M. Troyon ◽

P. Gallion

Keyword(s):

Electron Microscopy ◽

High Resolution ◽

Transfer Function ◽

Radiation Damage ◽

High Resolution Electron Microscopy ◽

Far Field ◽

Field Region ◽

Crystalline Materials ◽

Resolution Electron ◽

The Ideal

Two main problems in high resolution electron microscopy are first, the existence of gaps in the transfer function, and then the difficulty to find complex amplitude of the diffracted wawe from registered intensity. The solution of this second problem is in most cases only intended by the realization of several micrographs in different conditions (defocusing distance, illuminating angle, complementary objective apertures…) which can lead to severe problems of contamination or radiation damage for certain specimens.Fraunhofer holography can in principle solve both problems stated above (1,2). The microscope objective is strongly defocused (far-field region) so that the two diffracted beams do not interfere. The ideal transfer function after reconstruction is then unity and the twin image do not overlap on the reconstructed one.We show some applications of the method and results of preliminary tests.Possible application to the study of cavitiesSmall voids (or gas-filled bubbles) created by irradiation in crystalline materials can be observed near the Scherzer focus, but it is then difficult to extract other informations than the approximated size.

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Scanning Transmission Microscopy Applied to Thick Specimen

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100095510 ◽

1972 ◽

Vol 30 ◽

pp. 452-453

Author(s):

H. Koike ◽

T. Matsuo ◽

K. Ueno ◽

M. Suzuki

Keyword(s):

Psoas Muscle ◽

Image Intensifier ◽

Chromatic Aberration ◽

Image Contrast ◽

Transmission Microscopy ◽

Crystalline Materials ◽

Thick Specimen ◽

Transmission Electron ◽

Scanning Transmission ◽

Electron Microscope Image

Since the identification of single atoms was achieved by Crewe et al, scanning transmission microscopy has been put into pratical use. Recently they applied this method to the quantitative mass analysis of DNA.As pointed out previously the chromatic aberration which decreases the image contrast and quality, does not affect a scanning transmission image as it does a conventional transmission electron microscope image. Thus, the STEM method is advantageous for thick specimen. Further this method employs a high sensitive photomultiplier tube which also functions as an image intensifier. This detection method is effective for the observation of living specimens or easily damaged specimens. In this respect the scanning transmission microscope with high accelerating voltage is necessary.Since Uyeda's experiments of crystalline materials, many workers have been discussed how thick specimens can be observed by CTEM. With biological specimens, R. Szirmae reported on the decrease in the image contrast of rabbit psoas muscle sections at various accelerating voltages and specimen thicknesses.

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Voltage and Orientation Dependence of Characteristic X-Ray Production in Thin Crystals

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100118941 ◽

1985 ◽

Vol 43 ◽

pp. 414-415

Author(s):

G. Thomas ◽

K. M. Krishnan ◽

Y. Yokota ◽

H. Hashimoto

Keyword(s):

Standing Wave ◽

Incident Beam ◽

Orientation Dependence ◽

Incident Plane Wave ◽

Crystalline Materials ◽

X Ray ◽

Incident Plane ◽

Crystal Unit Cell ◽

Beam Orientation ◽

Acceleration Voltage

For crystalline materials, an incident plane wave of electrons under conditions of strong dynamical scattering sets up a standing wave within the crystal. The intensity modulations of this standing wave within the crystal unit cell are a function of the incident beam orientation and the acceleration voltage. As the scattering events (such as inner shell excitations) that lead to characteristic x-ray production are highly localized, the x-ray intensities in turn, are strongly determined by the orientation and the acceleration voltage. For a given acceleration voltage or wavelength of the incident wave, it has been shown that this orientation dependence of the characteristic x-ray emission, termed the “Borrmann effect”, can also be used as a probe for determining specific site occupations of elemental additions in single crystals.

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