scholarly journals Surface film X-ray microanalysis

Scanning ◽  
1990 ◽  
Vol 12 (4) ◽  
pp. 212-224 ◽  
Author(s):  
J. L. Pouchou ◽  
F. Pichoir
Keyword(s):  
Surface Film ◽  
X Ray

scholarly journals Thickness Determination of Surface Film for Textured Specimens by X-ray Diffraction

1997 ◽  
Vol 30 (1-2) ◽  
pp. 71-79 ◽  
Author(s):  
Liu Yu-Shu ◽  
Zhao Yu
Keyword(s):  
Surface Film ◽  
Diffraction Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thickness Determination

A simple and convenient X-ray diffraction method is proposed to determine the thickness of surface film for textured specimens. The analysis result for a synthetic specimen with surface film has proved that the method is applicable and reliable.

X-Ray Diffraction under Specular Reflection Conditions on Crystals with an Amorphous Surface Film

1984 ◽  
Vol 81 (1) ◽  
pp. 47-53 ◽  
Author(s):  
P. A. Aleksandrov ◽  
A. M. Afanasiev ◽  
M. K. Melkonyan ◽  
S. A. Stepanov
Keyword(s):  
Specular Reflection ◽  
Surface Film ◽  
X Ray Diffraction ◽  
X Ray ◽  
Amorphous Surface

Electrochemical and Spectroscopie Evaluation of Lithium Intercalation in Tailored Polymethacrylonitrile Carbons

1997 ◽  
Vol 496 ◽  
Author(s):  
Kevin R. Zavadil ◽  
Ronald A. Guidotti ◽  
William R. Even
Keyword(s):  
Photoelectron Spectroscopy ◽  
Bound States ◽  
Secondary Ion Mass Spectrometry ◽  
Surface Film ◽  
Lithium Ion ◽  
Irreversible Loss ◽  
X Ray ◽  
The Third ◽  
Secondary Ion ◽  
Voltammetric Measurements

AbstractDisordered polymethacrylonitrile (PMAN) carbon monoliths have been studied as potential tailored electrodes for lithium ion batteries. A combination of electrochemical and surface spectroscopie probes have been used to investigate irreversible loss mechanisms. Voltammetric measurements show that Li intercalates readily into the carbon at potentials IV positive of the reversible Li potential. The coulometric efficiency rises rapidly from 50% for the first potential cycle to greater than 85% for the third cycle, indicating that solvent decomposition is a self-limiting process. Surface film composition and thickness, as measured by x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS), does not vary substantially when compared to more ordered carbon surfaces. Li+ profiles are particularly useful in discriminating between the bound states of Li at the surface of solution permeable PMAN carbons.

X-ray Photoelectron Spectroscopy (XPS) Investigation of the Surface Film on Magnesium Powders

2012 ◽  
Vol 66 (5) ◽  
pp. 510-518 ◽  
Author(s):  
Paul J. Burke ◽  
Zeynel Bayindir ◽  
Georges J. Kipouros
Keyword(s):  
Surface Layer ◽  
Photoelectron Spectroscopy ◽  
Focused Ion Beam ◽  
Surface Film ◽  
Ion Beam ◽  
Pure Magnesium ◽  
Atmospheric Conditions ◽  
Magnesium Powder ◽  
X Ray ◽  
Aerospace Applications

Magnesium (Mg) and its alloys are attractive for use in automotive and aerospace applications because of their low density and good mechanical properties. However, difficulty in forming magnesium and the limited number of available commercial alloys limit their use. Powder metallurgy may be a suitable solution for forming near-net-shape parts. However, sintering pure magnesium presents difficulties due to surface film that forms on the magnesium powder particles. The present work investigates the composition of the surface film that forms on the surface of pure magnesium powders exposed to atmospheric conditions and on pure magnesium powders after compaction under uniaxial pressing at a pressure of 500 MPa and sintering under argon at 600 °C for 40 minutes. Initially, focused ion beam microscopy was utilized to determine the thickness of the surface layer of the magnesium powder and found it to be ∼10 nm. The X-ray photoelectron analysis of the green magnesium sample prior to sintering confirmed the presence of MgO, MgCO3·3H2O, and Mg(OH)2 in the surface layer of the powder with a core of pure magnesium. The outer portion of the surface layer was found to contain MgCO3·3H2O and Mg(OH)2, while the inner portion of the layer is primarily MgO. After sintering, the MgCO3·3H2O was found to be almost completely absent, and the amount of Mg(OH)2 was also decreased significantly. This is postulated to occur by decomposition of the compounds to MgO and gases during the high temperature of sintering. An increase in the MgO content after sintering supports this theory.

scholarly journals Mechanism of Li2S formation and dissolution in Lithium-Sulphur batteries

2021 ◽  
Author(s):  
Christian Prehal ◽  
Sara Drvarič Talian ◽  
Alen Vizintin ◽  
Heinz Amenitsch ◽  
Robert Dominko ◽  
...  
Keyword(s):  
High Performance ◽  
Surface Film ◽  
Rate Capability ◽  
Stochastic Modelling ◽  
Phase Evolution ◽  
Saxs Data ◽  
X Ray ◽  
X Ray Scattering ◽  
Chemical Phase

Abstract Insufficient understanding of the mechanism that reversibly converts sulphur into lithium sulphide (Li2S) via soluble polysulphides (PS) hampers the realization of high performance lithium-sulphur cells. Typically Li2S formation is explained by direct electroreduction of a PS to Li2S; however, this is not consistent with the size of the insulating Li2S deposits. Here, we use in situ small and wide angle X-ray scattering (SAXS/WAXS) to track the growth and dissolution of crystalline and amorphous deposits from atomic to sub-micron scales during charge and discharge. Stochastic modelling based on the SAXS data allows quantification of the chemical phase evolution during discharge and charge. We show that Li2S deposits predominantly via disproportionation of transient, solid Li2S2 to form primary Li2S crystallites and solid Li2S4 particles. We further demonstrate that this process happens in reverse during charge. These findings show that the discharge capacity and rate capability in Li-S battery cathodes are therefore limited by mass transport through the increasingly tortuous network of Li2S / Li2S4 / carbon pores rather than electron transport through a passivating surface film.

scholarly journals On the Beneficial Effect of MgCl2 as Electrolyte Additive to Improve the Electrochemical Performance of Li4Ti5O12 as Cathode in Mg Batteries

Nanomaterials ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 484 ◽  
Author(s):  
Marta Cabello ◽  
Gregorio Ortiz ◽  
Pedro Lavela ◽  
José Tirado
Keyword(s):  
Electrochemical Performance ◽  
Structural Changes ◽  
Surface Film ◽  
Practical Importance ◽  
Specific Capacity ◽  
Ex Situ ◽  
Insertion Reaction ◽  
Portable Devices ◽  
Active Electrode ◽  
X Ray

Magnesium batteries are a promising technology for a new generation of energy storage for portable devices. Attention should be paid to electrolyte and electrode material development in order to develop rechargeable Mg batteries. In this study, we report the use of the spinel lithium titanate or Li4Ti5O12 (LTO) as an active electrode for Mg2+-ion batteries. The theoretical capacity of LTO is 175 mA h g−1, which is equivalent to an insertion reaction with 1.5 Mg2+ ions. The ability to enhance the specific capacity of LTO is of practical importance. We have observed that it is possible to increase the capacity up to 290 mA h g−1 in first discharge, which corresponds to the reaction with 2.5 Mg2+ ions. The addition of MgCl2·6H2O to the electrolyte solutions significantly improves their electrochemical performance and enables reversible Mg deposition. Ex-situ X-ray diffraction (XRD) patterns reveal little structural changes, while X-ray photoelectron spectrometer (XPS) (XPS) measurements suggest Mg reacts with LTO. The Ti3+/Ti4+ ratio increases with the amount of inserted magnesium. The impedance spectra show the presence of a semicircle at medium-low frequencies, ascribable to Mg2+ ion diffusion between the surface film and LTO. Further experimental improvements with exhaustive control of electrodes and electrolytes are necessary to develop the Mg battery with practical application.

scholarly journals On the early stages of localised atmospheric corrosion of magnesium–aluminium alloys

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
M. Shahabi-Navid ◽  
Y. Cao ◽  
J. E. Svensson ◽  
A. Allanore ◽  
N. Birbilis ◽  
...  
Keyword(s):  
Magnesium Alloys ◽  
Photoelectron Spectroscopy ◽  
Aluminium Alloys ◽  
Atmospheric Corrosion ◽  
Surface Film ◽  
Pure Magnesium ◽  
X Ray Diffraction ◽  
Precipitation Mechanism ◽  
X Ray ◽  
Film Thinning

AbstractThe surface film on pure magnesium and two aluminium-containing magnesium alloys was characterised after 96 h at 95% RH and 22 °C. The concentration of CO2 was carefully controlled to be either 0 or 400 ppm. The exposed samples were investigated using X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and electron microscopy. The results showed that when the alloys were exposed to the CO2-containing environment, aluminium cations (Al3+) was incorporated into a layered surface film comprising a partially “hydrated” MgO layer followed by Mg(OH)2, and magnesium hydroxy carbonates. The results indicated that aluminium-containing magnesium alloys exhibited considerably less localised corrosion in humid air than pure magnesium. Localised corrosion in the materials under investigation was attributed to film thinning by a dissolution/precipitation mechanism.

The Study of Tribological Performance and Surface Film Characterization of Bismuth Dioctyldithiocarbamate

1996 ◽  
Vol 436 ◽  
Author(s):  
Chen Ligeong ◽  
Dong Junxiu ◽  
Chen Guoxu
Keyword(s):  
Photoelectron Spectroscopy ◽  
Friction And Wear ◽  
Iron Sulfide ◽  
Surface Film ◽  
X Ray ◽  
Tribological Behaviors ◽  
Reducing Ability ◽  
Inorganic Species ◽  
Metallic Bismuth ◽  
Block Test

AbstractIn this study, bismuth dioctyldithiocarbamate has been synthesized, and Its tribological behaviors, such as friction-reducing ability, antiwear property and extreme pressure performance have been respectively evaluated with a ring-on-block test rig and a fourball machine. In addition to correlate its tribological behaviors with the film formed on the metallic rubbing surface under boundary lubrication conditions, surface analyses have been conducted to characterize the surface film by means of Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy(XPS) and energy dispersion of X-ray (EDX).Test results show the additive compound can effectively improve the friction and wear of the rubbing couples. On the other hand, EDX confirmed the presence of carbon, oxygen, sulfur, nitrogen, bismuth and iron on the surface; AES revealed their depth distribution of atomic concentration percentages. Whereas XPS further disclosed that the composition of the surface film was composed of organic and inorganic species including iron sulfide and sulfate, metallic bismuth, bismuth oxide and sulfide etc. which are conducive to the reduction of friction and wear.

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