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.

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.

scholarly journals Effect of Cr Layer on the Structure and Properties of Cr/DLC Films

2016 ◽  
Vol 18 (4) ◽  
pp. 275
Author(s):  
Xiaohong Jiang ◽  
A.V. Rogachev ◽  
D.G. Piliptsou
Keyword(s):  
Crystal Surface ◽  
Chemical Properties ◽  
Carbon Films ◽  
Substantial Improvement ◽  
Structure And Properties ◽  
Double Crystal ◽  
Angle Measurements ◽  
Contact Angle Measurements ◽  
Arc Deposition ◽  
And Chemical Properties

This paper focuses on the Cr interlayer effect on the structure and properties of Cr/DLC films. To improve structural, mechanical and chemical properties of a-C films, we developed two layer chromium-carbon films produced by cathode magnetic filtered arc deposition. Microstructure and properties of these films are explained depending on the Cr-interlayer size. The structure is analyzed by Raman spectroscopy. Moreover, we also estimated residual stress, the friction coefficient, hardness, the elastic modulus and corrosion parameters by X-ray double crystal surface profilometry, tribotesting, nanoindenter-testing, as well as contact angle measurements and potentiodynamic polarization analysis. As a result of the comparative analysis, we revealed a substantial improvement in the characteristics of the produced two layer films. The results provide theoretical basis for the application of these films.

Convergent Beam Electron Diffraction

1978 ◽  
Vol 36 (3) ◽  
pp. 304-315
Author(s):  
G. Lehmpfuhl
Keyword(s):  
Electron Diffraction ◽  
Diffraction Pattern ◽  
Crystal Surface ◽  
Diffraction Spot ◽  
Crystal Thickness ◽  
Large Area ◽  
Electron Microscopic ◽  
Additional Information ◽  
Microscopic Investigations

Introduction In electron microscopic investigations of crystalline specimens the direct observation of the electron diffraction pattern gives additional information about the specimen. The quality of this information depends on the quality of the crystals or the crystal area contributing to the diffraction pattern. By selected area diffraction in a conventional electron microscope, specimen areas as small as 1 µ in diameter can be investigated. It is well known that crystal areas of that size which must be thin enough (in the order of 1000 Å) for electron microscopic investigations are normally somewhat distorted by bending, or they are not homogeneous. Furthermore, the crystal surface is not well defined over such a large area. These are facts which cause reduction of information in the diffraction pattern. The intensity of a diffraction spot, for example, depends on the crystal thickness. If the thickness is not uniform over the investigated area, one observes an averaged intensity, so that the intensity distribution in the diffraction pattern cannot be used for an analysis unless additional information is available.

scholarly journals Scalable nanoporous carbon films allow line-of-sight 3D atomic layer deposition of Pt: towards a new generation catalyst layer for PEM fuel cells

2021 ◽  
Author(s):  
Marwa Atwa ◽  
Xiaoan Li ◽  
Zhaoxuan Wang ◽  
Samuel Dull ◽  
Shicheng Xu ◽  
...  
Keyword(s):  
Atomic Layer Deposition ◽  
Pt Nanoparticles ◽  
Catalyst Layer ◽  
Atomic Layer ◽  
Pem Fuel Cells ◽  
Nanoporous Carbon ◽  
Carbon Films ◽  
Layer Deposition ◽  
Binder Free ◽  
New Generation

A self-supported, binder-free and scalable nanoporous carbon scaffold serves as an excellent host for the efficient and uniform atomic layer deposition of Pt nanoparticles, showing exemplary performance as a cathode catalyst layer in a PEM fuel cell.

Large Area Surface Treatment by Ion Beam Technology

1996 ◽  
Vol 438 ◽  
Author(s):  
R. L. C. Wu ◽  
W. Lanter
Keyword(s):  
Ion Beam ◽  
High Vacuum ◽  
Polycrystalline Diamond ◽  
Carbon Films ◽  
Ultra High Vacuum ◽  
Diamond Like Carbon ◽  
Chemical Compositions ◽  
Rf Power ◽  
Large Area ◽  
Ion Energy

AbstractAn ultra high vacuum ion beam system, consisting of a 20 cm diameter Rf excilted (13.56 MHz) ion gun and a four-axis substrate scanner, has been used to modify large surfaces (up to 1000 cm2) of various materials, including; infrared windows, silicon nitride, polycrystalline diamond, 304 and 316 stainless steels, 440C and M50 steels, aluminum alloys, and polycarbonates; by depositing different chemical compositions of diamond-like carbon films. The influences of ion energy, Rf power, gas composition (H2/CH4 , Ar/CH4 and O2/CH4/H2), on the diamond-like carbon characteristics has been studied. Particular attention was focused on adhesion, environmental effects, IR(3–12 μm) transmission, coefficient of friction, and wear factors under spacelike environments of diamond-like carbon films on various substrates. A quadrupole mass spectrometer was utilized to monitor the ion beam composition for quality control and process optimization.

scholarly journals Global metabolomic and lipidomic analysis reveals the potential mechanisms of hemolysis effect of Ophiopogonin D and Ophiopogonin D' in vivo

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Huan-Hua Xu ◽  
Zhen-Hong Jiang ◽  
Cong-Shu Huang ◽  
Yu-Ting Sun ◽  
Long-Long Xu ◽  
...  
Keyword(s):  
Chemical Properties ◽  
Principal Component ◽  
Partial Least Square ◽  
Least Square ◽  
Practical Significance ◽  
Plasma Metabolites ◽  
Active Components ◽  
The Difference

Abstract Background OPD and OPD' are the two main active components of Ophiopogon japonicas in Shenmai injection (SMI). Being isomers of each other, they are supposed to have similar pharmacological activities, but the actual situation is complicated. The difference of hemolytic behavior between OPD and OPD' in vivo and in vitro was discovered and reported by our group for the first time. In vitro, only OPD' showed hemolysis reaction, while in vivo, both OPD and OPD' caused hemolysis. In vitro, the primary cause of hemolysis has been confirmed to be related to the difference between physical and chemical properties of OPD and OPD'. In vivo, although there is a possible explanation for this phenomenon, the one is that OPD is bio-transformed into OPD' or its analogues in vivo, the other one is that both OPD and OPD' were metabolized into more activated forms for hemolysis. However, the mechanism of hemolysis in vivo is still unclear, especially the existing literature are still difficult to explain why OPD shows the inconsistent hemolysis behavior in vivo and in vitro. Therefore, the study of hemolysis of OPD and OPD' in vivo is of great practical significance in response to the increase of adverse events of SMI. Methods Aiming at the hemolysis in vivo, this manuscript adopted untargeted metabolomics and lipidomics technology to preliminarily explore the changes of plasma metabolites and lipids of OPD- and OPD'-treated rats. Metabolomics and lipidomics analyses were performed on ultra-high performance liquid chromatography (UPLC) system tandem with different mass spectrometers (MS) and different columns respectively. Multivariate statistical approaches such as principal component analysis (PCA) and orthogonal partial least square-discriminant analysis (OPLS-DA) were applied to screen the differential metabolites and lipids. Results Both OPD and OPD' groups experienced hemolysis, Changes in endogenous differential metabolites and differential lipids, enrichment of differential metabolic pathways, and correlation analysis of differential metabolites and lipids all indicated that the causes of hemolysis by OPD and OPD' were closely related to the interference of phospholipid metabolism. Conclusions This study provided a comprehensive description of metabolomics and lipidomics changes between OPD- and OPD'-treated rats, it would add to the knowledge base of the field, which also provided scientific guidance for the subsequent mechanism research. However, the underlying mechanism require further research.

scholarly journals Synthesis of the Sparse Uniform-Amplitude Concentric Ring Transmitting Array for Optimal Microwave Power Transmission

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Hua-Wei Zhou ◽  
Xue-Xia Yang ◽  
Sajjad Rahim
Keyword(s):  
Microwave Power ◽  
Large Scale ◽  
Power Transmission ◽  
Synthesis Method ◽  
Pso Algorithm ◽  
Practical Significance ◽  
Concentric Ring ◽  
Swarm Optimization ◽  
Key Factor ◽  
Feed Network

Beam capture efficiency (BCE) is one key factor of the overall efficiency for a microwave power transmission (MPT) system, while sparsification of a large-scale transmitting array has a practical significance. If all elements of the transmitting array are excited uniformly, the fabrication, maintenance, and feed network design would be greatly simplified. This paper describes the synthesis method of the sparse uniform-amplitude transmitting array with concentric ring layout using particle swarm optimization (PSO) algorithm while keeping a higher BCE. Based on this method, uniform exciting strategy, reduced number of elements, and a higher BCE are achieved simultaneously for optimal MPT. The numerical results of the sparse uniform-amplitude concentric ring arrays (SUACRAs) optimized by the proposed method are compared with those of the random-located uniform-amplitude array (RLUAA) and the stepped-amplitude array (SAA), both being reported in the literatures for the maximum BCE. Compared to the RLUAA, the SUACRA saves 32% elements with a 1.1% higher BCE. While compared to the SAA, the SUACRA saves 29.1% elements with a bit higher BCE. The proposed SUACRAs have higher BCEs, simple array arrangement and feed network, and could be used as the transmitting array for a large-scale MPT system.

scholarly journals TiO2-Coated ZnO Nanowire Arrays: A Photocatalyst with Enhanced Chemical Corrosion Resistance

Catalysts ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1289
Author(s):  
Lan Gao ◽  
Elyes Nefzaoui ◽  
Frédéric Marty ◽  
Mazen Erfan ◽  
Stéphane Bastide ◽  
...  
Keyword(s):  
Chemical Stability ◽  
Large Scale ◽  
Organic Dyes ◽  
Synthesis Method ◽  
Atomic Layer ◽  
Strong Acid ◽  
Tio2 Coating ◽  
High Chemical ◽  
Chemical Corrosion ◽  
High Chemical Stability

Photocatalysis is proven to be the most efficient and environmentally friendly method for the degradation of organic pollutants in water purification. To meet the requirement of large-scale water treatment, there are two important points: One is the lifetime and chemical stability of the photocatalyst material, especially in the complex and harsh aqueous conditions. The other is the ease of synthesis of such photocatalysts with specific nano-morphology. In this work, two common photocatalyst materials, zinc oxide (ZnO) and titanium dioxide (TiO2), are selected to form more sustainable photocatalysts with high chemical stability. This involves the combination of both TiO2 and ZnO in a two-step simple synthesis method. It appears advantageous to exploit the conformal deposition of atomic layer deposition (ALD) to achieve nanometer-thick TiO2 coating on ZnO nanowires (NWs) with a high aspect ratio, which are firmly anchored to a substrate and exhibit a large specific surface area. The high chemical stability of the ALD TiO2 coating has been investigated in detail and proven to be effective under both strong acid and strong alkaline aqueous solutions. In addition, photocatalysis experiments with organic dyes show that via this simple two-step synthesis method, the produced ZnO/TiO2 tandem does indeed exhibit improved chemical stability in a harsh environment, while allowing efficient photodegradation.

scholarly journals Synthesis and characterization of Mo2 C based materials over activated carbon derived from sewage sludge pyrolysis for catalytic applications

Cerâmica ◽  
2018 ◽  
Vol 64 (370) ◽  
pp. 148-155
Author(s):  
A. C. Alexandrino ◽  
J. F. de Sousa ◽  
C. P. de Souza ◽  
C. P. B. de Araújo ◽  
M. V. M. Souto
Keyword(s):  
Sewage Sludge ◽  
Surface Area ◽  
Synthesis Method ◽  
Metal Catalyst ◽  
Catalytic Material ◽  
Metal Support ◽  
Size Evaluation ◽  
Adsorption Desorption ◽  
Substitute Materials

Abstract Transition metal carbides have been successfully used as substitute materials for conventional noble metal catalyst in several important industrial reactions due to their interesting physicochemical properties. Surface structure, chemical composition and metal-support interactions, as well as processing conditions, are of utmost importance in the use of such materials in catalysis. The present study aimed to synthesize and evaluate pure molybdenum carbide with and without support, and bimetallic Mo-Ni carbide over a carbon active support derived from sewage sludge pyrolysis. The support was chemically (KOH) and physically (thermal treatment) activated before use. TG/DTG, XRD, XRF, SEM, BET and particle size evaluation were performed, together with adsorption/desorption isotherms. Results indicated that the applied synthesis method was adequate for the obtainment of pure materials. The increase in surface area of the support was significant, from 13 to 141 m².g-1 after the thermal and chemical treatment; also, supporting Mo2C over carbon provided an increase from 45 to 73 m².g-1 in surface area, which indicated its potential as a catalytic material as well as the effectiveness of the applied methodology.

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