scholarly journals Получение тонких пленок графита на диэлектрической подложке с помощью гетероэпитаксиального синтеза

2020 ◽  
Vol 46 (10) ◽  
pp. 38
Author(s):  
И.А. Сорокин ◽  
Д.В. Колодко ◽  
В.А. Лузанов ◽  
Е.Г. Шустин
Keyword(s):  
Chemical Etching ◽  
Metal Film ◽  
Catalytic Decomposition ◽  
Dielectric Substrate ◽  
Metal Catalyst ◽  
Structure Defects ◽  
Graphite Film ◽  
Crystal Structure Defects ◽  
Monocrystalline Film ◽  
Subsequent Diffusion

The results of testing the methods of preparation of thin graphite films on a dielectric substrate by the method of annealing the structure of (0001) Al2O3/(111) Ni/ta-C are present. The method is based on catalytic decomposition of hydrocarbons on the surface of the monocrystalline film of the metal-catalyst on the surface of the dielectric substrate and subsequent diffusion and crystallization of carbon between the metal film and the substrate. After chemical etching of the metal film, a thin graphite film with low density of crystal structure defects on a dielectric substrate is obtained.

Production of thin graphite films on a dielectric substrate by heteroepitaxial synthesis

2021 ◽  
Author(s):  
I.A. Sorokin ◽  
D.V. Kolodko ◽  
E.G. Shustin ◽  
V.A. Luzanov
Keyword(s):  
Crystal Surface ◽  
Synthesis Method ◽  
Chemical Properties ◽  
Catalytic Decomposition ◽  
Atomic Layer ◽  
Dielectric Substrate ◽  
Carbon Films ◽  
Practical Significance ◽  
Metal Catalyst ◽  
Large Area

Problem statement. Development of methods for producing large-area isolated graphene under controlled conditions is an important task, which is primarily interested in the unique physical and chemical properties of graphene: high electrical and thermal conductivity, dependence of electronic characteristics on the presence of attached different radicals on the graphene surface, adjustable band gap, and high carrier mobility. Goal. It is necessary to develop regimes for producing thin graphite films on a dielectric substrate by annealing the structure (0001)Al2O3/(111)Ni/ta-C with a minimum density of defects in the crystal structure by the heteroepitaxial synthesis method. Results. The method of obtaining thin graphite films on a dielectric substrate by annealing the structure (0001)Al2O3/(111)Ni/ta-C has been tested. The method is based on the catalytic decomposition of hydrocarbons on the single crystal surface of a metal catalyst, diffusion and crystallization of carbon on the reverse side of the metal film. The surface of the obtained carbon films with a thickness significantly exceeding one atomic layer is uniform within the 5x5 mm samples. Varying the annealing temperature and time, as well as the initial amount of carbon, will further allow to control the amount of carbon involved in the formation of atomic layers. Practical significance. The described method is promising for developing a scalable technological process for obtaining largearea graphene on a dielectric substrate.

NUMERICAL MODELING OF RADIATION EXPOSURE ON A QUARTZ CRYSTAL STRUCTURE DEFECTS AND SIGNAL ANALYSIS THERMOLUMINESCENT

2020 ◽  
Vol 6 (4) ◽  
pp. 158-178
Author(s):  
Vladimir S. Sheinkman ◽  
Yuliya Yu. Erina ◽  
Oleg A. Simonov
Keyword(s):  
Crystal Structure ◽  
Radiation Exposure ◽  
Electron Concentration ◽  
Numerical Experiments ◽  
Quartz Crystal ◽  
Equilibrium Concentration ◽  
Band Model ◽  
Structure Defects ◽  
Crystal Structure Defects ◽  
Intense Radiation

Developing thermoluminescent (TL) dating methods for quartz-containing deposits has required a series of numerical experiments within the framework of the band model to study the rate of electron accumulation in quartz crystal structure defects under radioactive radiation. The crystal model contained two different types of electron traps and one emission center. A system of differential equations was solved numerically, relating the rates of change in the electron concentration in defects of the crystal structure and the electron concentration in the conduction band and holes in the valence band. The results have shown that the intense radiation exposure alters the dynamic equilibrium concentration of electrons in the traps, which significantly modifies the TL signal. In accordance with this, the sensitivity marker material to the radioactive dose, required for absolute dating and received by its intense radiation exposure, cannot be determined correctly. In addition, the numerical experiments have confirmed the possibility of dating the samples by the position of the TL signal’s maximum on the time axis, as well as the possibility of obtaining the dating by the TL signal’s amplitude.

scholarly journals Catalytic Oxidation Process for the Degradation of Synthetic Dyes: An Overview

2019 ◽  
Vol 16 (11) ◽  
pp. 2066 ◽  
Author(s):  
Rahat Javaid ◽  
Umair Yaqub Qazi
Keyword(s):  
Catalytic Oxidation ◽  
Catalytic Decomposition ◽  
Metal Catalyst ◽  
Synthetic Dyes ◽  
Wastewater Discharge ◽  
Oxidation Processes ◽  
Tubular Reactors ◽  
Iron Metal ◽  
Degradation Of Dyes ◽  
Coloring Agents

Dyes are used in various industries as coloring agents. The discharge of dyes, specifically synthetic dyes, in wastewater represents a serious environmental problem and causes public health concerns. The implementation of regulations for wastewater discharge has forced research towards either the development of new processes or the improvement of available techniques to attain efficient degradation of dyes. Catalytic oxidation is one of the advanced oxidation processes (AOPs), based on the active radicals produced during the reaction in the presence of a catalyst. This paper reviews the problems of dyes and hydroxyl radical-based oxidation processes, including Fenton’s process, non-iron metal catalysts, and the application of thin metal catalyst-coated tubular reactors in detail. In addition, the sulfate radical-based catalytic oxidation technique has also been described. This study also includes the effects of various operating parameters such as pH, temperature, the concentration of the oxidant, the initial concentration of dyes, and reaction time on the catalytic decomposition of dyes. Moreover, this paper analyzes the recent studies on catalytic oxidation processes. From the present study, it can be concluded that catalytic oxidation processes are very active and environmentally friendly methods for dye removal.

Some examples of polyoxometalates crystal structure defects

2011 ◽  
Vol 67 (a1) ◽  
pp. C807-C807
Author(s):  
G. Leitus ◽  
L. J. W. Shimon ◽  
Y. Diskin-Posner ◽  
A. M. Khenkin ◽  
R. Neumann
Keyword(s):  
Crystal Structure ◽  
Structure Defects ◽  
Crystal Structure Defects

Effect of Catalyst Calcination Temperature on the Synthesis of MWCNTs-Talc Hybrid Compound Using CVD Method

2013 ◽  
Vol 594-595 ◽  
pp. 63-67
Author(s):  
Siti Shuhadah Mohd Saleh ◽  
Hazizan Md Akil ◽  
Ramdziah Md. Nasir ◽  
Muhammad Razlan Zakaria ◽  
Muhammad Helmi Abdul Kudus
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Source ◽  
Calcination Temperature ◽  
Chemical Vapour ◽  
Catalytic Decomposition ◽  
Metal Catalyst ◽  
Hybrid Compound ◽  
Calcination Temperatures ◽  
Cvd Method ◽  
Multi Walled Carbon Nanotubes

Carbon nanotubes-talc (CNTs-talc) hybrid compound has been successfully synthesized via chemical vapour deposition (CVD) method. A gas mixture of methane/nitrogen (CH4/N2) was used as the carbon source and nickel as the metal catalyst for the growth of CNT hybrid compound. Talc works as substrate or support material which is combined with nickel to form a complex metal-talc catalyst that will react with carbon source to produce the hybrid compound. To study the effect of different calcinations temperature, four different calcinations temperature, 300 °C (C-talc300), 500 °C (C-talc500), 700 °C (C-talc700) and 900 °C (C-talc900) were used. Among these four calcination temperatures for synthesis the multi-walled carbon nanotubes (MWCNTs), C-talc500 is the most optimum calcination temperature to perform catalytic decomposition by reacting in methane atmosphere at 800 °C to produce the CNT-talc hybrid compound.

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