scholarly journals Isothermal and Two-Temperature Zone Selenization of Mo Layers

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
L. Kaupmees ◽  
M. Altosaar ◽  
O. Volobujeva ◽  
T. Raadik ◽  
M. Grossberg ◽  
...  
Keyword(s):  
Vapor Pressure ◽  
Film Thickness ◽  
Oxygen Content ◽  
Power Function ◽  
Temperature Zone ◽  
Type Conductivity ◽  
Residual Oxygen ◽  
Two Temperature ◽  
Selenization Process ◽  
Residual Oxygen Content

Glass/Mo, Mo foil, glass/Mo/In, and glass/Mo/Cu stacked layers were selenized in closed vacuum tubes by isothermal and/or two-temperature zone annealing in Se vapors. The selenization process was studied dependent on Se vapor pressure, temperature and time. Samples were selenized from 375 to 580°C for 30 and 60 minutes. The applied Se pressure was varied between 130 and4.4⋅103 Pa. The increase of MoSe2film thickness was found to depend on the origin of Mo. MoSe2thicknessdLon Mo-foil was much higher than on sputtered Mo layers, and it depended linearly on time and as a power functiondL~PSe1/2on Se vapor pressure. The residual oxygen content in the formed MoSe2layers was much lower in the two-zone selenization process. If Mo was covered with Cu or In before selenization, these were found to diffuse into formed MoSe2layer. All the MoSe2layers showedp-type conductivity.

Radiative And Nonradiative Relaxation Of Excitons In GaN

1997 ◽  
Vol 482 ◽  
Author(s):  
A. Göldner ◽  
L. Eckey ◽  
A. Hoffmann ◽  
I. Broser ◽  
A. Alemu ◽  
...  
Keyword(s):  
Buffer Layer ◽  
Layer Thickness ◽  
Oxygen Content ◽  
Quantum Efficiency ◽  
Bulk Material ◽  
Sample Thickness ◽  
Nonradiative Relaxation ◽  
Residual Oxygen ◽  
Buffer Layer Thickness ◽  
Residual Oxygen Content

AbstractWe report on investigations of the excitonic quantum efficiency in GaN epilayers as function of buffer layer thickness, buffer layer material, sample thickness and residual oxygen content. These values are compared to that of GaN bulk material. The quantum efficiency of the free excitons rises with increasing buffer layer thickness, increasing sample thickness and decreasing residual oxygen content. The influence of oxygen on the quantum efficiency is stronger than that of the buffer layer thickness. Additionally, the homoepitaxial growth of GaN shows higher quantum efficiencies than the growth with an AIN buffer layer. In general, the observed quantum efficiencies in GaN epilayers are below 20% indicating the strong impact of nonradiative relaxation and recombination processes in the excitonic range. Only, GaN bulk material shows quantum efficiencies of 25 % for the free A-exciton XA and of 50 % for the donor-bound exciton complex D0,X).

scholarly journals Electron beam welding of rectangular copper wires applied in electrical drives

2021 ◽  
Author(s):  
Tamás Tóth ◽  
Jonas Hensel ◽  
Sven Thiemer ◽  
Philipp Sieber ◽  
Klaus Dilger
Keyword(s):  
Electron Beam ◽  
Oxygen Content ◽  
Electron Beam Welding ◽  
Base Material ◽  
Fusion Welding ◽  
Eb Welding ◽  
Technological Parameters ◽  
Low Level ◽  
Residual Oxygen ◽  
Ofe Copper

AbstractThe so-called hairpin winding technology, which is specially tailored to electrical traction components, deploys rectangular plug-in copper wires in the stator. The fusion welding of the adjacent wire ends is associated with challenges due to the high thermal conductivity as well as the porosity formation of the copper. During this study, the electron beam (EB) welding of electrolytic tough pitch (ETP) and oxygen-free electronic grade (OFE) copper connectors was investigated. Subsequently, the specimens underwent X-ray computed tomography (CT) and metallographic examinations to characterize the joints. It was discovered that the residual oxygen content of the base material is responsible for the pore formation. With only a very low level of oxygen content in the copper, a porosity- and spatter-free welding can be reproducibly realized using the robust EB welding technology, especially for copper materials. By optimizing the parameters accordingly, joints exhibiting a low level of porosity were achieved even in the case of the alloy containing a high amount of residual oxygen. Beyond this, detailed analyses in terms of pore distribution were carried out and a good correlation between technological parameters and welding results was determined.

Effects of ultra-high-temperature (UHT) processing and of subsequent storage on the vitamin content of milk

1969 ◽  
Vol 36 (3) ◽  
pp. 447-454 ◽  
Author(s):  
J. E. Ford ◽  
J. W. G. Porter ◽  
S. Y. Thompson ◽  
Joyce Toothill ◽  
J. Edwards-Webb
Keyword(s):  
Ascorbic Acid ◽  
Folic Acid ◽  
High Temperature ◽  
Oxygen Content ◽  
Raw Milk ◽  
Vitamin B ◽  
Vitamin Content ◽  
Residual Oxygen ◽  
Subsequent Storage ◽  
Ultra High Temperature

SummaryThe vitamin content of ultra-high-temperature (UHT) processed milk was compared with that of the original raw milk. Three processes were used. In the first, which caused no change in oxygen content, the milk was heated and cooled in a plate-type heat exchanger. In the second, the milk was again heated indirectly and then evaporatively cooled, leaving in the milk about one-third of the initial oxygen content. In the third process the milk was heated by direct steam injection and cooled by evaporation and contained little or no residual oxygen.On processing and during subsequent storage for 90 days there was no loss of vitamin A, carotene, vitamin E, thiamine, riboflavine, pantothenic acid, biotin or nicotinic acid. There was little or no loss of vitamin B6or vitamin B12on processing, but up to 50% of each of these vitamins was lost during 90 days' storage. All the dehydroascorbic acid (DHA) and about 20% of the ascorbic acid (AA) was lost on processing. There was no further loss of AA during 90 days’ storage when no residual oxygen was present, but in milks containing more than about 1 ppm oxygen all the AA was lost within 14 days. About 20% of the folic acid was lost on processing; thereafter, as with ascorbic acid, the extent of the loss on storage depended on the residual oxygen content of the milk: in the absence of oxygen the folic acid was stable.

Synthesis of polycrystalline CdSiP2 with Two-Temperature zone method

2020 ◽  
Vol 529 ◽  
pp. 125271 ◽  
Author(s):  
Kui Cheng ◽  
Guodong Zhang ◽  
Zhongjun Zhai ◽  
Longzhen Zhang ◽  
Peng Zhang ◽  
...  
Keyword(s):  
Temperature Zone ◽  
Zone Method ◽  
Two Temperature

scholarly journals Modeling the Response of Canopy Stomatal Conductance to Humidity

2009 ◽  
Vol 10 (2) ◽  
pp. 521-532 ◽  
Author(s):  
Shusen Wang ◽  
Yan Yang ◽  
Alexander P. Trishchenko ◽  
Alan G. Barr ◽  
T. A. Black ◽  
...  
Keyword(s):  
Water Vapor ◽  
Stomatal Conductance ◽  
Relative Humidity ◽  
Vapor Pressure ◽  
Power Function ◽  
Vapor Pressure Deficit ◽  
Water Vapor Pressure ◽  
Nonlinear Function ◽  
Environmental Variable ◽  
Water Vapor Pressure Deficit

Abstract Humidity of air is a key environmental variable in controlling the stomatal conductance (g) of plant leaves. The stomatal conductance–humidity relationships employed in the Ball–Woodrow–Berry (BWB) model and the Leuning model have been widely used in the last decade. Results of independent evaluations of the two models vary greatly. In this study, the authors develop a new diagnostic parameter that is based on canopy water vapor and CO2 fluxes to assess the response of canopy g to humidity. Using eddy-covariance flux measurements at three boreal forest sites in Canada, they critically examine the performance of the BWB and the Leuning models. The results show that the BWB model, which employs a linear relationship between g and relative humidity (hs), leads to large underestimates of g when the air is wet. The Leuning model, which employs a nonlinear function of water vapor pressure deficit (Ds), reduced this bias, but it still could not adequately capture the significant increase of g under the wet conditions. New models are proposed to improve the prediction of canopy g to humidity. The best performance was obtained by the model that employs a power function of Ds, followed by the model that employs a power function of relative humidity deficit (1 − hs). The results also indicate that models based on water vapor pressure deficit generally performed better than those based on relative humidity. This is consistent with the hypothesis that the stomatal aperture responds to leaf water loss because water vapor pressure deficit rather than relative humidity directly affects the transpiration rate of canopy leaves.

Kinetic Effects of Methanol Addition on the Formation and Consumption of Formaldehyde and Benzene in Premixed n-Heptane/Air Flames

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Ge Hu ◽  
Shiyong Liao ◽  
Zhaohong Zuo ◽  
Kun Wang ◽  
Zhengbing Zhu
Keyword(s):  
Low Temperature ◽  
Atmospheric Pressure ◽  
Kinetic Scheme ◽  
Temperature Zone ◽  
Obvious Effect ◽  
Production And Consumption ◽  
Conversion Rates ◽  
C3 Species ◽  
Kinetic Effects ◽  
Two Temperature

A numerical investigation was conducted to explore the kinetic effects of methanol addition on the formation and consumption of formaldehyde and benzene in premixed stoichiometric n-heptane/air flames at atmospheric pressure. The flame modeling was performed by solving the premixed flame model with a comprehensive kinetic scheme of hydrocarbon fuels. We studied the species distributions, formation temperatures, temperature sensitivities, reaction contributions, and the rates of production and consumption for formaldehyde and benzene. Results showed that formaldehyde and benzene were produced in two temperature zones and the accumulation effect in the low-temperature zone was the most important factor for the peak concentrations of them in flames. When methanol was added into n-heptane/air flames, cross-reactions were hardly found in the formation routes of formaldehyde and benzene. Both the increased peak concentration and the decreased formation temperature of formaldehyde were primarily attributed to the fact that CH3O (+M) <=>CH2O + H (+M) and CH2OH + O2<=>CH2O + HO2 were promoted in low-temperature zone. Methanol addition decreased the rates of production and consumption of benzene proportionally, and served as a diluent fuel in benzene formation and consumption. CH3, CH3O, CH2OH, C3H3, and A-C3H5 were the most important precursors for the formation of formaldehyde and benzene. The conversion rates of these species into formaldehyde and benzene were explored as well. Results showed that methanol addition suppressed the conversion of C3 species into benzene, but it hardly showed obvious effect on the conversion of CH3, CH3O, and CH2OH into formaldehyde.

Synthesis of New Alkali-Metal-Intercalated Layered-Silicate Compounds and Their Magnetic Properties

1996 ◽  
Vol 453 ◽  
Author(s):  
N. Wada ◽  
Hideaki Okui ◽  
Yasuyuki Omura ◽  
Akihiko Fujiwara ◽  
Hiroyoshi Suematsu ◽  
...  
Keyword(s):  
Alkali Metals ◽  
Layered Silicate ◽  
Metallic Silver ◽  
X Ray Diffraction ◽  
Temperature Zone ◽  
X Ray ◽  
Intercalated Compounds ◽  
Field Evidence ◽  
Pauli Paramagnetism ◽  
Two Temperature

AbstractSingle crystals and powders of vermiculite are dehydrated and then intercalated with alkali metals (K and Rb) using a two-temperature-zone furnace. The samples, originally transparent, exhibit metallic silver color upon intercalation. Our x-ray diffraction experiments indicate that the c-axis lattice constant becomes smaller after the intercalation process. A SQUID magnetometer is used to measure the magnetization of the samples as functions of temperature and magnetic field. Evidence for Pauli paramagnetism and enhancement of ferromagnetism are found in the Rb- and K-intercalated compounds, in addition to Curie paramagnetism due to iron impurities in the original vermiculite.

scholarly journals Impact of Bio-Ethanol, Bio-ETBE Addition on the Volatility of Gasoline with Oxygen Content at the Level of E10

Fuels ◽  
2021 ◽  
Vol 2 (4) ◽  
pp. 501-520
Author(s):  
Dimitra-Panagiota Michalopoulou ◽  
Maria Komiotou ◽  
Ypatia Zannikou ◽  
Dimitrios Karonis
Keyword(s):  
Vapor Pressure ◽  
Beneficial Effect ◽  
Oxygen Content ◽  
Test Methods ◽  
Unleaded Gasoline ◽  
Specification Limits ◽  
Simultaneous Addition ◽  
Ethanol Content ◽  
The Impact

This study examines the impact of the addition of bio-ethanol/bio-ETBE on the main volatility properties of gasoline. Although several studies have been published on the addition of ethanol or ETBE to gasoline, the simultaneous addition of these oxygenates has not been studied by taking the maximum oxygen content of 3.7% m/m into account. The EN 228:2012-A1:2017 standard specifies the requirements for marketed unleaded gasoline. This standard is able to determine, among other things, a gasoline type with a maximum oxygen content of 3.7% m/m and sets the maximum limits for ethanol content at 10% v/v and 22% v/v for ethers with a minimum five carbon atoms, such as ΕΤΒΕ. Five refinery fractions were mixed in various proportions and were used as base fuels. A total of 30 samples were prepared by blending the base fuels with bio-ethanol/bio-ETBE. In each of these base fuels, bio-ethanol was added in concentrations up to 10% v/v. Subsequently, bio-ETBE was added to each of these fuels in concentrations up to 20.8% v/v for use as a stabilizer. All of the samples were examined using the EN ISO 13016-1 and EN ISO 3405 test methods while considering the volatility requirements set by EN 228. The results showed that the addition of bio-ETBE has a beneficial effect on the volatility characteristics of the samples, as it reduces the vapor pressure of the final blend and sets all fuels in compliance with the required specification limits set by the EN 228 standard.

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