scholarly journals Demixing in the plasma created in capillary discharges with polymeric wall

2021 ◽  
Vol 2100 (1) ◽  
pp. 012002
Author(s):  
A S Pashchina
Keyword(s):  
Thermal Diffusion ◽  
Diffusion Processes ◽  
Chemical Elements ◽  
Diffusion Mechanism ◽  
Peripheral Region ◽  
Capillary Wall ◽  
Spectral Diagnostics ◽  
Common Sign ◽  
Favorable Conditions ◽  
Central High

Abstract The results of spectral diagnostics of erosion plasma obtained in a pulsed discharge in a capillary with an evaporating wall made of hydrogen-carbon and fluorine-carbon polymers - polymethylmethacrylate and polytetrafluoroethylene - are presented. It was found that in both cases the distribution of chemical elements along the discharge radius is highly inhomogeneous, and their concentration ratio differs significantly from that in the capillary wall. The mass of particles is a common sign characterizing the demixing degree of chemical elements and direction of diffusion flows in fluorine-carbon and hydrogen-carbon plasmas. In both cases, lightweight particles are concentrated in the central high-temperature region, while heavy ones run away onto the low-temperature peripheral region of the discharge. Estimates show that the thermal diffusion mechanism is quite capable for providing the observed demixing degree of chemical elements. Favorable conditions for thermal diffusion processes are formed in the layer adjacent to the capillary wall, where the intense dissociation of radicals occurs, and the temperature gradient reaches up to ΔT∼10 eV/mm.

Dissipation of mechanical energy in a deformable solid during thermal-diffusion processes

1973 ◽  
Vol 5 (1) ◽  
pp. 1-6
Author(s):  
Ya. S. Podstrigach ◽  
R. N. Shvets ◽  
V. S. Pavlina ◽  
Ya. I. Dasyuk
Keyword(s):  
Thermal Diffusion ◽  
Diffusion Processes ◽  
Mechanical Energy ◽  
Deformable Solid

scholarly journals Na2Fe3(SO4)4 as a new high-voltage potential cathode material for sodium-ion batteries

2021 ◽  
Vol 130 (1B) ◽  
pp. 59-67
Author(s):  
Thien Lan Tran ◽  
Huu Duc Luong ◽  
Trong Lam Pham ◽  
Viet Bac Phung ◽  
Van An Dinh
Keyword(s):  
Cathode Material ◽  
High Voltage ◽  
Density Functional ◽  
Diffusion Processes ◽  
Small Polaron ◽  
Diffusion Mechanism ◽  
Sodium Ion ◽  
Structure Stability ◽  
Sodium Ion Batteries ◽  
Significant Difference

Based on the density functional theory, we propose a promising cathode material, Na2Fe3(SO4)4, applicable for sodium-ion batteries. The crystal structure, stability, average voltage, and diffusion mechanism are carefully investigated to evaluate the electrochemical properties. The proposed material exhibits a high voltage of 4.0 V during the Na extraction. A small polaron is proved to be formed preferably at the first nearest Fe sites to Na vacancy and simultaneously accompanies the Na vacancy during its migration. Four elementary diffusion processes of the polaron–Na vacancy complexes, namely two parallel and two crossing processes, have been explored. The significant difference of activation energies between parallel and crossing processes suggests the substantial effect of the small polaron migration on the Na vacancy diffusion. We found that the parallel process along the [001] direction has the lowest activation energy of 808 meV, implying that the Na vacancy preferably diffuses in a zigzag pathway along the [001] direction.

scholarly journals Study of diffusion processes in the oxide layer of zirconium alloys

2016 ◽  
Vol 60 (1) ◽  
pp. 1-5
Author(s):  
P. Sialini ◽  
P. Sajdl ◽  
V. Havránek ◽  
V. Vrtílková
Keyword(s):  
Nuclear Reactor ◽  
Diffusion Processes ◽  
Ion Beam ◽  
Diffusion Mechanism ◽  
Zirconium Alloys ◽  
Corrosion Layer ◽  
Particle Accelerator ◽  
Element Analysis ◽  
Physics Institute ◽  
Decomposition Reactions

Abstract In the active zone of a nuclear reactor where zirconium alloys are used as a coating material, this material is subject to various harmful impacts. During water decomposition reactions, hydrogen and oxygen are evolved that may diffuse through the oxidic layer either through zirconium dioxide (ZrO2) crystals or along ZrO2 grains. The diffusion mechanism can be studied using the Ion Beam Analysis (IBA) method where nuclear reaction 18O(p,α)15N is used. A tube made of zirconium alloy E110 (with 1 wt. % of Nb) was used for making samples that were pre-exposed in UJP PRAHA a.s. and subsequently exposed to isotopically cleansed environment of H2 18O medium in an autoclave. The samples were analysed with gravimetric methods and IBA methods performed at the electrostatic particle accelerator Tandetron 4130 MC in the Nucler Physics Institute of the CAS, Řež. With IBA methods, the overall thicknesses of corrosion layers on the samples, element composition of the alloy and distribution of oxygen isotope 18O in the corrosion layer and its penetration in the alloy were identified. The retrieved data shows at the oxygen diffusion along ZrO2 grains because there are two peaks of 18O isotope concentrations in the corrosion layer. These peaks occur at the environment-oxide and oxide-metal interface. The element analysis identified the presence of undesirable hafnium.

THE SURFACE AND INTERFACE PROPERTIES OF VANADIUM CARBIDE COATING PREPARED BY THERMAL DIFFUSION PROCESS

2011 ◽  
Vol 10 (01) ◽  
pp. 183-190 ◽  
Author(s):  
DEJUN KONG ◽  
CHAOZHENG ZHOU
Keyword(s):  
Thermal Diffusion ◽  
Vanadium Carbide ◽  
Chemical Elements ◽  
Energy Dispersive Spectrometer ◽  
Salt Bath ◽  
Bonding Interface ◽  
Surface And Interface ◽  
Coating Surface ◽  
Bonding Method ◽  
Vanadium Carbide Coating

Vanadium carbide (VC) coating is prepared with Thermal Diffusion (TD) method in the salt bath, and its surface-interface microstructures and energy spectrums were observed with Scanning Electron Microscope (SEM) and Energy Dispersive Spectrometer (EDS), respectively, and the distributions of C , V , Cr , Si , Fe , and Mo in VC coating interface are analyzed. Its interfacial and bonding methods are discussed, and the bonding micromechanism of VC coating in its bonding interface by TD process is analyzed. The experimental results show that the structure of coating surface by TD is single-phase, that is composed of V and C elements, and no other elements, the chemical elements such as V , Cr , C Si , Fe , Mo are the grade distributed in its bonding interface; its bonding method is metallurgical status; microhardness of coating-substrate is the grade distribution, which is direct ratio with the V distribution, microhardness of the coating surface is 3050–3200 HV, and the effect of TD process on roughness of cold-working die surface is little.

A Physical Route to High Performance Heterojunction Composites: Experiments, Mechanism and Applications

MRS Advances ◽  
2016 ◽  
Vol 1 (6) ◽  
pp. 441-446
Author(s):  
Delong Li ◽  
Chengzhi Luo ◽  
Chunxu Pan
Keyword(s):  
High Temperature ◽  
Thermal Diffusion ◽  
High Performance ◽  
Diffusion Mechanism ◽  
Research Area ◽  
Research Progress ◽  
Photocatalytic Efficiency ◽  
Important Research ◽  
Oxide Semiconductors ◽  
Important Research Area

ABSTRACTIn order to enhance the photocatalytic efficiency of oxide semiconductors, variant processes have been proposed. The creation of the heterojunction composites has attracted considerable attentions and developed into an important research area for the high performance photocatalyst preparation. In this paper, we introduce the research progress on heterojunction composites which were prepared via a novel physical route with relatively high temperature treatments. It is hope that this mini-review can inspire research interest in the realm of heterojunction synthesis based on the thermal diffusion mechanism.

Mechanical-thermal diffusion processes in the surface layer of a plate in application of a eutectic coating

1988 ◽  
Vol 24 (2) ◽  
pp. 114-119
Author(s):  
A. R. Gachkevich ◽  
V. M. Golubets ◽  
B. I. Gornyi ◽  
O. N. Makarenko
Keyword(s):  
Surface Layer ◽  
Thermal Diffusion ◽  
Diffusion Processes ◽  
Eutectic Coating

InGaN Laser Diode Degradation. Surface and Bulk Processes

2009 ◽  
Vol 1195 ◽  
Author(s):  
Piotr Perlin ◽  
Łucja Marona ◽  
Przemek Wisniewski ◽  
Mike Leszczynski ◽  
Pawel Prystawko ◽  
...  
Keyword(s):  
Diffusion Processes ◽  
Diffusion Mechanism ◽  
Laser Diodes ◽  
Photochemical Reactions ◽  
Extended Defects ◽  
Degradation Mechanisms ◽  
Electrical Stress ◽  
Physical Effects ◽  
P Type ◽  
Exposed Facets

AbstractWe discuss main degradation mechanisms present in nitride based laser diodes operating in 400-440 nm spectral range. We can clearly divide the aging processes into these occurring on the exposed facets of the device and into the bulk phenomena. Surface processes are predominantly connected with photochemical reactions on the laser mirrors and manifest by the formation of the carbon deposits. The nature of these photochemical reactions resembles very closely the mechanism known as Package Induced Failure observed previously in case of 980 nm laser diodes. Degradation involving bulk like effects is much less understood. The experimental results by other group are not sufficient for proposing an unambiguous model of the physical effects involved. In particular, it consists in observation related to dopants diffusion and recombination mechanisms. Magnesium diffusion from the p-type layers into the active layer was proposed as a possible degradation path. However, our study of SIMS profiles in the device subjected to over 8 000 h of electrical stress reveals no visible modification in the Mg profile. The same holds for the hydrogen spatial distribution thus substantially limiting candidates for the diffusion processes. Nevertheless, it seems that the diffusion mechanism is involved in bulk degradation. The claim is supported by two facts: well confirmed stability of the extended defects network in nitride emitters and characteristic square-root time-dependence of the degradation rate.

Sign in / Sign up

Export Citation Format

Share Document