scholarly journals The growth of epitaxial uranium oxide observed by micro-Raman spectroscopy

2005 ◽  
Vol 893 ◽  
Author(s):  
Niña Caculitan ◽  
Wigbert J. Siekhaus
Keyword(s):  
Raman Spectroscopy ◽  
Optical Properties ◽  
Oxide Layer ◽  
Uranium Oxide ◽  
Signal Amplitude ◽  
Oxide Thickness ◽  
Grain Structure ◽  
Raman Signal ◽  
Oxide Growth ◽  
Micro Raman Spectroscopy

AbstractRaman spectroscopy can be performed with micrometer resolution and can thus be used to determine the dependence of oxide thickness on the substrate’s grain structure or local impurity inclusions. The Raman signal amplitude emitted from an epitaxial uranium oxide layer as a function of oxide thickness has been modeled for light of 632.8 nm wavelength incident on the oxide and reflected from the uranium substrate using the optical properties determined by spectrophotometry. The model shows that the Raman signal increases with oxide thickness and saturates at about 150 nm thickness. The model was compared with the measured Raman signal amplitude of an epitaxial uranium oxide layer growing in air with a known time dependence of oxide growth.

scholarly journals Micro-Raman Spectroscopy of Dental Implants Subjected to Different Surface Treatments

2020 ◽  
Vol 10 (7) ◽  
pp. 2417 ◽  
Author(s):  
Saturnino Marco Lupi ◽  
Pietro Galinetto ◽  
Benedetta Albini ◽  
Elisa Di Ronza ◽  
Silvana Rizzo ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Dental Implants ◽  
Biological Response ◽  
Oxide Thickness ◽  
Surface Treatments ◽  
Amorphous Oxide ◽  
Additional Information ◽  
Micro Raman Spectroscopy ◽  
Amorphous Tio2 ◽  
Proportional Increase

The aim of the study was to qualitatively investigate the structure of the surface layer of TiO2 on dental implants made of Ti-6Al-4V subjected to different manufacturing treatments. M (machined), B (Al2O3-blasted), E (HNO3\HF-etched), B + E and A (B + E + anodized) implants and a further group receiving the same treatments as the first group with the addition of a final decontamination with cold plasma were included in the study. Examination was performed using micro-Raman spectroscopy. The surface treatments evaluated did not achieve the formation of crystalline TiO2. The increase in the complexity of surface treatment produced a proportional increase in the thickness of amorphous TiO2 oxide. In the B + E group, the plasma treatment enhanced the amorphous oxide thickness of TiO2. The other surfaces treated by plasma decontamination did not show a difference to the respective untreated ones. The investigated surface treatments did not change the crystalline cage of TiO2 in Ti-6Al-4V implants but affected the thickness of the oxide layer. The biological response could be influenced by different oxide thicknesses. Additional information on superficial TiO2 structural organization can be obtained by micro-Raman evaluation of dental implants. Dental implants with B + E + plasma and A superficial treatments allowed the maximum formation of the amorphous oxide thickness.

A mechanistic model for oxide growth and dissolution during corrosion of Cr-containing alloys

2015 ◽  
Vol 180 ◽  
pp. 113-135 ◽  
Author(s):  
M. Momeni ◽  
J. C. Wren
Keyword(s):  
Metal Oxide ◽  
Oxide Layer ◽  
Metal Cation ◽  
Corrosion Behaviour ◽  
Mechanistic Model ◽  
Potential Drop ◽  
Oxide Thickness ◽  
Oxide Growth ◽  
Metal Oxidation ◽  
Charge Balance

We have developed a corrosion model that can predict metal oxide growth and dissolution rates as a function of time for a range of solution conditions. Our model considers electrochemical reactions at the metal/oxide and oxide/solution interfaces, and the metal cation flux from the metal to the solution phase through a growing oxide layer, and formulates the key processes using classical chemical reaction rate or flux equations. The model imposes mass and charge balance and hence, is labeled as the Mass Charge Balance (MCB) model. Mass and charge balance dictate that at any given time the oxidation (or metal cation) flux must be equal to the sum of the oxide growth flux and the dissolution flux. For each redox reaction leading to the formation of a specific oxide, the metal oxidation flux is formulated using a modified Butler–Volmer equation with an oxide-thickness-dependent effective overpotential. The oxide growth and dissolution fluxes have a first-order dependence on the metal cation flux. The rate constant for oxide formation also follows an Arrhenius dependence on the potential drop across the oxide layer and hence decreases exponentially with oxide thickness. This model is able to predict the time-dependent potentiostatic corrosion behaviour of both pure iron, and Co–Cr and Fe–Ni–Cr alloys.

Modelling of Corrosion Induced Stresses during Zircaloy-4 Oxidation in Air

2008 ◽  
Vol 595-598 ◽  
pp. 419-427 ◽  
Author(s):  
Vincent Busser ◽  
Jean Desquines ◽  
Stéphanie Fouquet ◽  
Marie Christine Baietto ◽  
Jean Paul Mardon
Keyword(s):  
Oxide Layer ◽  
Research Work ◽  
Oxide Thickness ◽  
Stress Profile ◽  
Oxide Growth ◽  
Large Set ◽  
Transient Experiments ◽  
Cracking Mechanisms ◽  
Oxidation In Air ◽  
Good Agreement

In the frame of its research work on nuclear fuel safety, the French “Institut de Radioprotection et de Sûreté Nucléaire” (IRSN) has highlighted the importance of cladding tube oxidation on its thermomechanical behavior. The occurrence of radial cracking and spallation has been observed as the main mechanisms for the zirconia layer degradation during transient experiments. A study of these two mechanisms has been jointly launched by IRSN and Areva-NP. Thus laboratory air oxidations of fully recrystallized or stress-relieved low-tin Zircaloy-4 cladding tubes have been performed. Representative oxide layer thicknesses varying from 10 to 100 0m have been obtained. SEM micrographs of the obtained oxidised samples show that short circumferential cracks are periodically distributed in the oxide thickness. For specimens with oxide film thickness greater than 30 0m, radial cracks are initiated from the outer surface of the oxide layer and propagated radially. Veins characterised by the lack of circumferentially orientated crack are evidenced. All these phenomena are mainly linked to high compressive stress levels in the zirconia layer. A model describing the stress evolution in the oxide and in the cladding has been developed. This model takes into account the influence of elasticity, cladding creep, oxide growth and thermal expansion. Deflection tests data [15] are used to calibrate the oxide growth modelling. The model enables the evaluation of strain or stress profile in the oxide layer and in the base metal. Numerical results are in good agreement with a large set of axial and circumferential strains measurements. Further a better understanding of cracking mechanisms is achieved considering the good agreement between experimental and numerical analysis.

scholarly journals The optical properties of a polished uranium surface and its epitaxial oxide, and the rate of oxide growth determined by spectrophotometry

2005 ◽  
Vol 893 ◽  
Author(s):  
Wigbert J Siekhaus ◽  
Art J Nelson
Keyword(s):  
Optical Properties ◽  
Oxide Layer ◽  
Wide Band ◽  
Oxide Growth ◽  
Uranium Metal ◽  
Epitaxial Oxide

AbstractWide-band reflectrometry and ellipsometry have been used to determine the optical properties n and k of freshly polished uranium and of the epitaxial oxide layer, and also the rate of oxide growth in air. Results for uranium metal as well as for epitaxial oxide are compared with single wavelength ellipsometry literature values.

Effects of Fe doping on the strain and optical properties of GaN epilayers grown on sapphire substrates

RSC Advances ◽  
2014 ◽  
Vol 4 (98) ◽  
pp. 55430-55434 ◽  
Author(s):  
C. C. Zheng ◽  
J. Q. Ning ◽  
Z. P. Wu ◽  
J. F. Wang ◽  
D. G. Zhao ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Optical Properties ◽  
Geometric Configuration ◽  
Fe Doping ◽  
Micro Raman Spectroscopy ◽  
Sapphire Substrates ◽  
Back Scattering

The effects of Fe doping on a series of Fe-doped GaN epilayers with different doping concentrations grown on sapphire substrates were investigated in detail by confocal micro-Raman spectroscopy under the back-scattering geometric configuration.

Double Nanoparticle Layer in a 12th Century Lustreware Decoration: Accident or Technological Mastery?

2009 ◽  
Vol 8 ◽  
pp. 133-139 ◽  
Author(s):  
Philippe Sciau ◽  
Claude Mirguet ◽  
Christian Roucau ◽  
Delhia Chabanne ◽  
Max Schvoerer
Keyword(s):  
Electron Microscopy ◽  
Raman Spectroscopy ◽  
Optical Properties ◽  
Metallic Nanoparticles ◽  
Optical Devices ◽  
Spectroscopic Methods ◽  
Modern Equipment ◽  
Micro Raman Spectroscopy ◽  
Nanoparticle Layer ◽  
Made In

Metallic lustre decorations of glazed ceramics, which appeared in Mesopotamia during the 9th century AD, can be considered nowadays as an historical example of controlled nanotechnology for optical devices. Their surprising optical properties are directly due to metallic nanoparticles that Islamic potters were able to bury in the first layers of glaze through empirical chemical means. Lustre technology is fascinating and many papers have been devoted to this subject. Many lustre samples have been investigated with the most modern equipment such as the synchrotron radiation, electron microscopy, micro-Raman spectroscopy and other spectroscopic methods. This decor made in the twelfth century during the Fatimid dynasty shows a quasi-perfect double layer of nanoparticles confirming the high technological mastery of this civilization. Moreover, up to now, no lustre has been found with an organization of nanoparticles as elaborate as the decor presented here.

scholarly journals Composition of uranium oxide surface layers analyzed by μ-Raman Spectroscopy

2003 ◽  
Vol 802 ◽  
Author(s):  
Wigbert J. Siekhaus
Keyword(s):  
Raman Spectroscopy ◽  
Fourier Transform ◽  
Uranium Oxide ◽  
Diffuse Reflectance ◽  
High Sensitivity ◽  
Depth Resolution ◽  
Oxide Thickness ◽  
Oxide Surface ◽  
Surface Layers ◽  
The Past

AbstractOxide thickness and composition averaged over a few square millimeter have been measured with nm thickness resolution by diffuse reflectance Fourier transform infrared (FTIR) spectroscopy. μ-Raman spectroscopy has been done on powders and bulk samples in the past, and can now be done on surfaces layers with μm lateral and depth resolution using con-focal microscopy. Here we apply con-focal-microscopy-based μ -Raman spectroscopy to a freshly polished/lightly oxidized and to heavily oxidized uranium to determine its sensitivity. The spectra show that μ-Raman spectroscopy does detect oxide thickness and oxide composition with high sensitivity.

scholarly journals Dataset for SERS Plasmonic Array: Width, Spacing, and Thin Film Oxide Thickness Optimization

Data ◽  
2018 ◽  
Vol 3 (3) ◽  
pp. 37
Author(s):  
◽  
◽  
◽  
◽  
◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Silicon Dioxide ◽  
Computational Study ◽  
Oxide Thickness ◽  
Surface Enhanced Raman Spectroscopy ◽  
Raman Signal ◽  
Plasmonic Nanostructures ◽  
Gold Nanowires ◽  
Plasmonic Enhancement ◽  
Surface Enhancement

Surface-enhanced Raman spectroscopy (SERS) improves the scope and power of Raman spectroscopy by taking advantage of plasmonic nanostructures, which have the potential to enhance Raman signal strength by several orders of magnitude, which can allow for the detection of analyte molecules. The dataset presented provides results of a computational study that used a finite element method (FEM) to model gold nanowires on a silicon dioxide substrate. The survey calculated the surface average of optical surface enhancement due to plasmonic effects across the entire model and studied various geometric parameters regarding the width of the nanowires, spacing between the nanowires, and thickness of the silicon dioxide substrate. From this data, enhancement values were found to have a periodicity due to the thickness of the silicon dioxide. Additionally, strong plasmonic enhancement for smaller distances between nanowires were found, as expected; however, additional surface enhancement at greater gap distances were observed, which were not anticipated, possibly due to resonance with periodic dimensions and the frequency of the light. This data presentation will benefit future SERS studies by probing further into the computational and mathematical material presented previously.

Correlation Between the Tunnelling Oxide and I-V Curves of MIS Photodiodes

2003 ◽  
Vol 762 ◽  
Author(s):  
H. Águas ◽  
L. Pereira ◽  
A. Goullet ◽  
R. Silva ◽  
E. Fortunato ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Oxide Layer ◽  
Spectroscopic Ellipsometry ◽  
Chemical Deposition ◽  
Oxide Thickness ◽  
Electrical Performance ◽  
Signal To Noise ◽  
Rectification Factor ◽  
Mis Devices ◽  
The Ideal

AbstractIn this work we present results of a study performed on MIS diodes with the following structure: substrate (glass) / Cr (2000Å) / a-Si:H n+ (400Å) / a-Si:H i (5500Å) / oxide (0-40Å) / Au (100Å) to determine the influence of the oxide passivation layer grown by different techniques on the electrical performance of MIS devices. The results achieved show that the diodes with oxides grown using hydrogen peroxide present higher rectification factor (2×106)and signal to noise (S/N) ratio (1×107 at -1V) than the diodes with oxides obtained by the evaporation of SiO2, or by the chemical deposition of SiO2 by plasma of HMDSO (hexamethyldisiloxane), but in the case of deposited oxides, the breakdown voltage is higher, 30V instead of 3-10 V for grown oxides. The ideal oxide thickness, determined by spectroscopic ellipsometry, is dependent on the method used to grow the oxide layer and is in the range between 6 and 20 Å. The reason for this variation is related to the degree of compactation of the oxide produced, which is not relevant for applications of the diodes in the range of ± 1V, but is relevant when high breakdown voltages are required.

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