The Influence of Vacuum Annealing on the Nucleation and Growth Kinetics of Uranium Hydride

2012 ◽  
Vol 1444 ◽  
Author(s):  
J.P. Knowles ◽  
I.M. Findlay ◽  
D.A. Geeson ◽  
S.G. Bazley
Keyword(s):  
Photoelectron Spectroscopy ◽  
Vacuum Annealing ◽  
Unit Area ◽  
Specific Rate ◽  
Partial Reduction ◽  
Nucleation Kinetics ◽  
X Ray ◽  
Outer Oxide Layer ◽  
Hydrogen Exposure ◽  
Kinetics Of

ABSTRACTThe reaction kinetics of depleted uranium under constant hydrogen pressure (1 bar) have been measured as a function of reaction temperatures between 65 and 385 °C for as-polished and vacuum annealed samples. Enhanced hydrogen reactivity was observed on samples that underwent vacuum annealing prior to hydrogen exposure. The enhanced reactivity was found to be the result of enhanced nucleation rates on annealed samples since the specific rate per reacting unit area remained unaffected. X-ray photoelectron spectroscopy demonstrates that the nucleation kinetics were promoted on annealed samples as a result of the dehydration and partial reduction of the UO2+x outer oxide layer and the formation of an oxycarbide (UOxCy) sub-layer.

Xps Analysis of the Sapphire Surface as a Function of High Temperature Vacuum Annealing

1989 ◽  
Vol 159 ◽  
Author(s):  
E.D. Richmond
Keyword(s):  
High Temperature ◽  
Binding Energy ◽  
Photoelectron Spectroscopy ◽  
Vacuum Annealing ◽  
Xps Analysis ◽  
Chemical Changes ◽  
Cleaning Procedure ◽  
Sapphire Surface ◽  
X Ray ◽  
First Time

ABSTRACTFor the first time the (1102) surface of sapphire has been investigated by X-ray photoelectron spectroscopy to ascertain chemical changes resulting from annealing in vacuum at 1300° C and 1450° C. As received substrates had a substantial surface C contaminant. For substrates that were chemically cleaned before inserting them into the MBE system no trace of carbon is detected. A residual flourine contaminant results from the cleaning procedure and is desorbed by the vacuum annealing. Spectra of annealed substrates are compared to the unannealed chemically cleaned substrates. The annealed substrates exhibit 0.4 to 0.5 eV shift to higher binding energy of the Al peak and a 0.3 eV shift to higher binding energy of the O peak. In addition, a 2% depletion of oxygen from the surface occurs.

GROWTH OF OXIDE LAYER ON GERMANIUM (011) SUBSTRATE UNDER DRY AND WET ATMOSPHERES

1999 ◽  
Vol 06 (06) ◽  
pp. 1053-1060 ◽  
Author(s):  
N. TABET ◽  
J. AL-SADAH ◽  
M. SALIM
Keyword(s):  
Simple Model ◽  
Oxide Film ◽  
Growth Kinetics ◽  
Photoelectron Spectroscopy ◽  
Early Stage ◽  
X Ray ◽  
Apparent Thickness ◽  
Different Temperatures ◽  
Kinetics Of

X-ray Photoelectron Spectroscopy (XPS) has been used to investigate the oxidation of (011) Ge substrates. The sample surfaces were CP4-etched, then annealed in situ, at different temperatures, for various durations. Dry and wet atmospheres were used. The oxidation rate during the early stage was increased by the presence of moisture in the atmosphere. A simple model was used to define and determine an apparent thickness of the oxide film from XPS measurements. The time dependence of the apparent thickness is consistent with a partial coverage of the surface by oxide islands. The growth kinetics of the oxide islands obeys a nearly cubic law.

scholarly journals Enhanced removal of hexavalent chromium by different acid-modified biochar derived from corn straw: behavior and mechanism

2020 ◽  
Vol 81 (10) ◽  
pp. 2270-2280
Author(s):  
Yonggang Xu ◽  
Tianxia Bai ◽  
Yubo Yan ◽  
Yunfeng Zhao ◽  
Ling Yuan ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Hydrogen Ion ◽  
Corn Straw ◽  
Order Model ◽  
Freundlich Model ◽  
X Ray ◽  
Modified Biochar ◽  
Before And After ◽  
Pseudo Second Order ◽  
Kinetics Of

Abstract It is of great significance to remove Cr(VI) from water as a result of its high toxicity. Biochar from corn straw was modified by different acids (HNO3, H2SO4 and H3PO4) to remove Cr(VI) from aqueous solution. To estimate the removal mechanisms of Cr(VI) by the acid-modified biochars, batch experiments were performed in the light of contact time, Cr(VI) concentration, and pH, and the characteristics of acid-modified biochars before and after Cr(VI) adsorption were investigated by Fourier transform infrared spectra (FTIR) and X-ray photoelectron spectroscopy (XPS). The adsorption kinetics of Cr(VI) by acid-modified biochars were consistent with the pseudo-second-order model, and the adsorption isotherm obeyed the Freundlich model. Furthermore, the acid- modified biochars could supply more oxygen-containing functional groups (-COOH and -OH) as electron donor (e−) and hydrogen ion (H+) to enhance the reduction of Cr(VI) to Cr(III), resulting in enhanced removal of Cr(VI). HNO3-modified biochar exhibited the highest removal efficiency of Cr(VI). In general, the acid modifition of biochar was an effective method to increase the removal of Cr(VI).

scholarly journals Thermal Stability of Octadecyltrichlorosilane and Perfluorooctyltriethoxysilane Monolayers on SiO2

Nanomaterials ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 210
Author(s):  
Xiangdong Yang ◽  
Haitao Wang ◽  
Peng Wang ◽  
Xuxin Yang ◽  
Hongying Mao
Keyword(s):  
Thermal Stability ◽  
Thermal Behavior ◽  
Work Function ◽  
Photoelectron Spectroscopy ◽  
Vacuum Annealing ◽  
Moderate Temperature ◽  
Ultraviolet Photoelectron Spectroscopy ◽  
X Ray ◽  
Thermal Stability Of

Using in situ ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS) measurements, the thermal behavior of octadecyltrichlorosilane (OTS) and 1H, 1H, 2H, and 2H-perfluorooctyltriethoxysilane (PTES) monolayers on SiO2 substrates has been investigated. OTS is thermally stable up to 573 K with vacuum annealing, whereas PTES starts decomposing at a moderate temperature between 373 K and 423 K. Vacuum annealing results in the decomposition of CF3 and CF2 species rather than desorption of the entire PTES molecule. In addition, our UPS results reveal that the work function (WF)of OTS remains the same after annealing; however WF of PTES decreases from ~5.62 eV to ~5.16 eV after annealing at 573 K.

Application of V2O5 in Thin Film Microbatteries Prepared by RF Magnetron Sputtering

2009 ◽  
Vol 79-82 ◽  
pp. 931-934 ◽  
Author(s):  
Liang Tang Zhang ◽  
Jie Song ◽  
Quan Feng Dong ◽  
Sun Tao Wu
Keyword(s):  
Magnetron Sputtering ◽  
Photoelectron Spectroscopy ◽  
Unit Area ◽  
Rf Magnetron Sputtering ◽  
Micro Electro Mechanical System ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mems Technology ◽  
Surface Morphologies ◽  
Sputtering System

The polycrystalline V2O5 films as the anode in V2O5 /LiPON /LiCoO2 lithium microbattary were prepared by RF magnetron sputtering system. The V2O5 films’ crystal structures, surface morphologies and composition were characterized and analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The microbatteries were fabricated by micro electro-mechanical system (MEMS) technology. The battery active unit area is 500μm×500μm, and the thickness of V2O5, LiPON and LiCoO2 films was estimated to be 200, 610, and 220nm, respectively. The discharge volumetric capacity is between 9.36μAhcm-2μm-1 and 9.63μAhcm-2μm-1 after 40 cycles.

X-ray photoelectron spectroscopy study of the growth kinetics of biomimetically grown hydroxyapatite thin-film coatings

2010 ◽  
Vol 256 (23) ◽  
pp. 7178-7185 ◽  
Author(s):  
K. McLeod ◽  
S. Kumar ◽  
N.K. Dutta ◽  
R.St.C. Smart ◽  
N.H. Voelcker ◽  
...  
Keyword(s):  
Thin Film ◽  
Growth Kinetics ◽  
Photoelectron Spectroscopy ◽  
Spectroscopy Study ◽  
X Ray ◽  
Film Coatings ◽  
Thin Film Coatings ◽  
Kinetics Of

XPS AND XPD ANALYSIS OF NITROGEN ADSORPTION ON THE Ti(0001) SURFACE

1997 ◽  
Vol 04 (06) ◽  
pp. 1309-1314 ◽  
Author(s):  
D. P. FRICKEL ◽  
M. V. KUZNETSOV ◽  
E. V. SHALAEVA
Keyword(s):  
Photoelectron Spectroscopy ◽  
Titanium Surface ◽  
Nitrogen Adsorption ◽  
Text Structure ◽  
X Ray ◽  
Photoelectron Diffraction ◽  
The Third ◽  
Adsorption Temperature ◽  
Nearest Neighborhood ◽  
Kinetics Of

X-ray photoelectron spectroscopy (XPS) and X-ray photoelectron diffraction (XPD) were used to examine the kinetics of nitrogen adsorption on the Ti(0001) surface at temperatures from 220 to 570 K and adsorption exposures from 0 to 1000 L. At the adsorption temperature T=300 K two chemically nonequivalent states of nitrogen were found: NI (1×1 lattice) localized in octapores between the first and second titanium monolayers and NII (presumably [Formula: see text] structure) on the titanium surface. The third nitrogen state, N0 , which is also localized on the surface but has unoccupied octapores in the nearest neighborhood, is observed with a decrease in the adsorption temperature to 220 K. A model of nitrogen interaction with the Ti(0001) surface in vacuum was proposed proceeding from the temperature dependence of the kinetic adsorption curves.

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