scholarly journals THERMODIFFUSION SATURATION OF THE SURFACE LAYERS OF α-TITANIUM BY OXYGEN, NITROGEN, CARBON

2021 ◽  
pp. 65-72
Author(s):  
V.S. TRUSH ◽  
І. М. POHRELIUK ◽  
V.M. FEDIRKO
Keyword(s):  
Surface Layer ◽  
Saturation Temperature ◽  
Equilibrium Concentration ◽  
Surface Concentration ◽  
Concentration Profiles ◽  
Calculated Concentration ◽  
Near Surface ◽  
Diffusion Treatment ◽  
Alpha Titanium ◽  
Nonstationary Boundary

The purpose of the study is to analytically assess the depth of the gas-saturated zone in the case of a single-component diffusion saturation of alpha-titanium with nitrogen, oxygen and carbon from a rarefied controlled gas environment. Results. Based on the analysis of the literature data, the work schematically shows the interaction of alpha titanium with the elements of implementation and presents the processes with the corresponding parameters that characterize. It is shown that the surface impurity concentration is equal to the equilibrium concentration and is established instantly and does not depend on time. Consequently, with the proposed generalized nonstationary boundary condition in the absence of diffusion of impurities into the volume of the metal, the time dependence of its surface concentration is given, determined by the intensity of surface processes. The dependence of the relative change in the microhardness in the diffusion zone of titanium due to dissolved nitrogen (without taking into account the contribution of nitride inclusions) is presented. Analytically calculated concentration profiles of nitrogen generally correlate well with the distribution of the corresponding relative changes in microhardness in the surface layer. Analytical calculations of the concentration profiles of oxygen, nitrogen and carbon in titanium at a saturation temperature of 700 °C are presented. Practical value. The results obtained will make it possible to preliminarily estimate the size of the fortified near-surface layer depending on the parameters of chemical-thermal treatment and select the optimal parameters of thermal diffusion treatment to ensure the formation of reinforced layers on products made of alpha-titanium based on elements of interstitial in order to increase the functional properties.

Recombination Characteristics of Single-Crystalline Silicon Wafers with a Damaged Near-Surface Layer

2013 ◽  
Vol 58 (2) ◽  
pp. 142-150 ◽  
Author(s):  
A.V. Sachenko ◽  
◽  
V.P. Kostylev ◽  
V.G. Litovchenko ◽  
V.G. Popov ◽  
...  
Keyword(s):  
Surface Layer ◽  
Crystalline Silicon ◽  
Silicon Wafers ◽  
Single Crystalline Silicon ◽  
Near Surface ◽  
Single Crystalline

Investigation of the Hydrogen Transport Processes in Crystalline Silicon of n-Type Conductivity

2007 ◽  
Vol 131-133 ◽  
pp. 425-430 ◽  
Author(s):  
Anis M. Saad ◽  
Oleg Velichko ◽  
Yu P. Shaman ◽  
Adam Barcz ◽  
Andrzej Misiuk ◽  
...  
Keyword(s):  
Hydrogen Concentration ◽  
Room Temperature ◽  
Crystalline Silicon ◽  
Transport Processes ◽  
Concentration Profiles ◽  
Hydrogen Transport ◽  
Hydrogen Atoms ◽  
Near Surface ◽  
Type Conductivity ◽  
Hydrogen Molecules

The silicon substrates were hydrogenated at approximately room temperature and hydrogen concentration profiles vs. depth have been measured by SIMS. Czochralski grown (CZ) wafers, both n- and p-type conductivity, were used in the experiments under consideration. For analysis of hydrogen transport processes and quasichemical reactions the model of hydrogen atoms diffusion and quasichemical reactions is proposed and the set of equations is obtained. The developed model takes into account the formation of bound hydrogen in the near surface region, hydrogen transport as a result of diffusion of hydrogen molecules 2 H , diffusion of metastable complexes * 2 H and diffusion of nonequilibrium hydrogen atoms. Interaction of 2 H with oxygen atoms and formation of immobile complexes “oxygen atom - hydrogen molecule” (O - H2 ) is also taken into account to explain the hydrogen concentration profiles in the substrates of n-type conductivity. The computer simulation based on the proposed equations has shown a good agreement of the calculated hydrogen profiles with the experimental data and has allowed receiving a value of the hydrogen molecules diffusivity at room temperature.

scholarly journals Influence of the aerosol solar extinction on photochemistry during the 2010 Russian wildfires episode

2015 ◽  
Vol 15 (19) ◽  
pp. 10983-10998 ◽  
Author(s):  
J. C. Péré ◽  
B. Bessagnet ◽  
V. Pont ◽  
M. Mallet ◽  
F. Minvielle
Keyword(s):  
Transport Model ◽  
Regional Scale ◽  
Model Performance ◽  
Surface Concentration ◽  
Near Surface ◽  
Aerosol Mass ◽  
Aerosol Mass Concentration ◽  
Air Quality Measurements ◽  
Photolysis Rates ◽  
Optical Module

Abstract. In this work, impact of aerosol solar extinction on the photochemistry over eastern Europe during the 2010 wildfires episode is discussed for the period from 5 to 12 August 2010, which coincides to the peak of fire activity. The methodology is based on an online coupling between the chemistry-transport model CHIMERE (extended by an aerosol optical module) and the radiative transfer code TUV. Results of simulations indicate an important influence of the aerosol solar extinction, in terms of intensity and spatial extent, with a reduction of the photolysis rates of NO2 and O3 up to 50 % (in daytime average) along the aerosol plume transport. At a regional scale, these changes in photolysis rates lead to a 3–15 % increase in the NO2 daytime concentration and to an ozone reduction near the surface of 1–12 %. The ozone reduction is shown to occur over the entire boundary layer, where aerosols are located. Also, the total aerosol mass concentration (PM10) is shown to be decreased by 1–2 %, on average during the studied period, caused by a reduced formation of secondary aerosols such as sulfates and secondary organics (4–10 %) when aerosol impact on photolysis rates is included. In terms of model performance, comparisons of simulations with air quality measurements at Moscow indicate that an explicit representation of aerosols interaction with photolysis rates tend to improve the estimation of the near-surface concentration of ozone and nitrogen dioxide as well as the formation of inorganic aerosol species such as ammonium, nitrates and sulfates.

The Vacancy Generation Influence on the Initial Stage of Ion Implantation

2015 ◽  
Vol 1097 ◽  
pp. 29-34
Author(s):  
E.S. Parfenova ◽  
Anna G. Knyazeva
Keyword(s):  
Surface Layer ◽  
Ion Implantation ◽  
Metal Surface ◽  
Impurity Concentration ◽  
Coupled Model ◽  
Irreversible Processes ◽  
Concentration Profiles ◽  
Thermodynamics Of Irreversible Processes ◽  
Vacancy Generation ◽  
Initial Stage

The coupled model is presented to describe the elements penetration into the surface layer of metal during the process of ion implantation. Mechanical stresses arising due to the interaction of particles with the surface affect the redistribution of the implanted impurity. In addition, the existence of vacancies in the metal surface and their generation under the stresses influence are taken into account. The kinetic law is written on the basis of the thermodynamics of irreversible processes. The solution had been found numerically. As a result, the distributions of impurity concentration and deformations have been obtained for various time moments. The comparison of the concentration profiles with vacancies and without their have been given.

scholarly journals Enhanced Diffusion of Dopants in Vacancy Supersaturation Produced by MeV Implantation

1997 ◽  
Vol 469 ◽  
Author(s):  
V. C. Venezia ◽  
T. E. Haynes ◽  
A. Agarwal ◽  
H. -J. Gossmann ◽  
D. J. Eaglesham
Keyword(s):  
Surface Layer ◽  
Surface Region ◽  
Silicon On Insulator ◽  
Rich Region ◽  
Near Surface ◽  
Enhanced Diffusion ◽  
Float Zone ◽  
Transient Enhanced Diffusion

ABSTRACTThe diffusion of Sb and B markers has been studied in vacancy supersaturations produced by MeV Si implantation in float zone (FZ) silicon and bonded etch-back silicon-on-insulator (BESOI) substrates. MeV Si implantation produces a vacancy supersaturated near-surface region and an interstitial-rich region at the projected ion range. Transient enhanced diffusion (TED) of Sb in the near surface layer was observed as a result of a 2 MeV Si+, 1×1016/cm2, implant. A 4× larger TED of Sb was observed in BESOI than in FZ silicon, demonstrating that the vacancy supersaturation persists longer in BESOI than in FZ. B markers in samples with MeV Si implant showed a factor of 10× smaller diffusion relative to markers without the MeV Si+ implant. This data demonstrates that a 2 MeV Si+ implant injects vacancies into the near surface region.

Physical properties and spatial distribution of the sea ice surface layer (SSL/snow) during the autumn phase of the MOSAiC expedition

2021 ◽  
Author(s):  
Ruzica Dadic ◽  
Martin Schneebeli ◽  
Henna-Reeta Hannula ◽  
Amy Macfarlane ◽  
Roberta Pirazzini
Keyword(s):  
Surface Layer ◽  
Spatial Distribution ◽  
Sea Ice ◽  
Physical Properties ◽  
Surface Scattering ◽  
Climate Feedback ◽  
Energy Fluxes ◽  
Scattering Layer ◽  
Near Surface ◽  
Ice Surface

<p>Snow cover dominates the thermal and optical properties of sea ice and the energy fluxes between the ocean and the atmosphere, yet data on the physical properties of snow and its effects on sea ice are limited. This lack of data leads to two significant problems: 1) significant biases in model representations of the sea ice cover and the processes that drive it, and 2) large uncertainties in how sea ice influences the global energy budget and the coupling of climate feedback. The  MOSAiC research initiative enabled the most extensive data collection of snow and surface scattering layer (SSL) properties over sea ice to date. During leg 5 of the MOSAiC expedition, we collected multi-scale (microscale to 100-m scale) measurements of the surface layer (snow/SSL) over first year ice (FYI) and MYI on a daily basis. The ultimate goal of our measurements is to determine the spatial distribution of physical properties of the surface layer. During leg 5 of the MOSAiC expedition, that surface layer changed from the  surface scattering layer (SSL),   characteristic for the melt season, to an early autumn snow pack. Here,  we will present data showing both a) the physical properties and the spatial distribution of the SSL during the late melt season and b) the transition of the sea ice surface from the SSL to the fresh autumn snowpack. The structural properties of this transition period are poorly documented, and this season is critical  for the initialization of sea ice and snow models. Furthermore, these data are crucial to interpret simultaneous observations of surface energy fluxes, surface optical and remote sensing data (microwave signals in particular), near-surface biochemical activity, and to understand the sea ice  processes that occur as the sea ice transitions from melting to freezing.</p>

Deepening of domains at e-beam writing on the -Z surface of lithium niobate

2021 ◽  
Author(s):  
Lyudmila Kokhanchik ◽  
Evgenii Emelin ◽  
Vadim Vladimirovch Sirotkin ◽  
Alexander Svintsov
Keyword(s):  
Surface Layer ◽  
Electron Beam ◽  
Lithium Niobate ◽  
Electric Field ◽  
Domain Walls ◽  
Normal Component ◽  
Beam Current ◽  
Near Surface ◽  
Domain Structures ◽  
Sign Inversion

Abstract The focus of the study was to investigate the peculiarities of the domains created by electron beam (e-beam) in a surface layer of congruent lithium niobate, which comparable to a depth of electron beam charge penetration. Direct e-beam writing (DEBW) of different domain structures with a scanning electron microscope was performed on the polar -Z cut. Accelerating voltage 15 kV and e-beam current 100 pA were applied. Different patterns of local irradiated squares were used to create domain structures and single domains. No domain contrast was observed by the PFM technique. Based on chemical etching, it was found that the vertices of the domains created do not reach the surface level. The average deepening of the domain vertices was several hundred nanometers and varied depending on the irradiation dose and the location of the irradiated areas (squares) relative to each other. Computer simulation was applied to analyze the spatial distribution of the electric field in the various irradiated patterns. The deepening was explained by the fact that in the near-surface layer there is a sign inversion of the normal component of the electric field strength vector, which controls the domain formation during DEBW. Thus, with the help of e-beam, domains were created completely located in the bulk, in contrast to the domains that are nucleated on the surface of the -Z cut during the polarization inversion with AFM tip. The detected deepening of e-beam domains suggests the possibility of creating the “head-to-head” domain walls in the near-surface layer lithium niobate by DEBW.

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