Vapor-phase production of nanomaterials

2021 ◽  
Author(s):  
Mohammad Malekzadeh ◽  
Mark T. Swihart
Keyword(s):  
Vapor Phase ◽  
Advantages And Disadvantages ◽  
Aerosol Synthesis ◽  
Synthesis Of Nanomaterials ◽  
Phase Production

This review comprehensively treats aerosol synthesis of nanomaterials, highlighting advantages and disadvantages of different approaches with examples of materials produced.

scholarly journals Process Intensification Approach Using Microreactors for Synthesizing Nanomaterials—A Critical Review

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 98
Author(s):  
Vikas Hakke ◽  
Shirish Sonawane ◽  
Sambandam Anandan ◽  
Shriram Sonawane ◽  
Muthupandian Ashokkumar
Keyword(s):  
Critical Review ◽  
High Surface ◽  
Process Intensification ◽  
Volume Ratio ◽  
Continuous Mode ◽  
Segmented Flow ◽  
Advantages And Disadvantages ◽  
Nanomaterial Synthesis ◽  
Recent Developments ◽  
Synthesis Of Nanomaterials

Nanomaterials have found many applications due to their unique properties such as high surface-to-volume ratio, density, strength, and many more. This review focuses on the recent developments on the synthesis of nanomaterials using process intensification. The review covers the designing of microreactors, design principles, and fundamental mechanisms involved in process intensification using microreactors for synthesizing nanomaterials. The microfluidics technology operates in continuous mode as well as the segmented flow of gas–liquid combinations. Various examples from the literature are discussed in detail highlighting the advantages and disadvantages of microfluidics technology for nanomaterial synthesis.

scholarly journals Catalysts for the Conversion of CO2 to Low Molecular Weight Olefins—A Review

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6952
Author(s):  
Barbara Pawelec ◽  
Rut Guil-López ◽  
Noelia Mota ◽  
Jose Fierro ◽  
Rufino Navarro Yerga
Keyword(s):  
Value Added ◽  
Active Phase ◽  
Catalyst Design ◽  
Light Olefins ◽  
Petroleum Processing ◽  
Hydrogenation Of Co2 ◽  
Advantages And Disadvantages ◽  
Olefin Production ◽  
Synthesis Of Nanomaterials ◽  
Reaction Routes

There is a large worldwide demand for light olefins (C2=–C4=), which are needed for the production of high value-added chemicals and plastics. Light olefins can be produced by petroleum processing, direct/indirect conversion of synthesis gas (CO + H2) and hydrogenation of CO2. Among these methods, catalytic hydrogenation of CO2 is the most recently studied because it could contribute to alleviating CO2 emissions into the atmosphere. However, due to thermodynamic reasons, the design of catalysts for the selective production of light olefins from CO2 presents different challenges. In this regard, the recent progress in the synthesis of nanomaterials with well-controlled morphologies and active phase dispersion has opened new perspectives for the production of light olefins. In this review, recent advances in catalyst design are presented, with emphasis on catalysts operating through the modified Fischer–Tropsch pathway. The advantages and disadvantages of olefin production from CO2 via CO or methanol-mediated reaction routes were analyzed, as well as the prospects for the design of a single catalyst for direct olefin production. Conclusions were drawn on the prospect of a new catalyst design for the production of light olefins from CO2.

scholarly journals Nanocomposite Material Synthesized Via Horizontal Vapor Phase Growth Technique: Evaluation and Application Perspective

2021 ◽  
Author(s):  
Muhammad Akhsin Muflikhun ◽  
Rahmad Kuncoro Adi ◽  
Gil Nonato C. Santos
Keyword(s):  
Vapor Phase ◽  
Gas Sensing ◽  
Synthesis Method ◽  
Phase Growth ◽  
Growth Technique ◽  
Vapor Phase Growth ◽  
Technique Evaluation ◽  
Synthesized Materials ◽  
Source Materials ◽  
Synthesis Of Nanomaterials

The synthesis of nanomaterials has been reported by many researchers using different methods. One of the methods that can be used with perfect pureness and have less pollution in the synthesized materials results is the vapor phase growth technique (VPGT). Several types of nano shapes materials were reported such as nanoparticles, nanorods, nano triangular, nanosphere, and nanocrystal. The synthesis method has a fundamental process where the nanomaterials evaporated and condensed based on the temperature difference. There are three important variables, i.e., stochiometric ratio of source materials, temperature and baking time. The synthesis was occured in the quartz tube and sealed in the vacuum condition. This create the material was synthesis in pure and isolated conditions. The application of the nanomaterials synthesized via Horizontal Vapor Phase Growth (HVPG) can be implemented in anti-pathogen, anti-bacterial, gas sensing and coating applications.

Cryogenic atomic force microscopy

1991 ◽  
Vol 49 ◽  
pp. 54-55
Author(s):  
K. A. Fisher ◽  
M. G. L. Gustafsson ◽  
M. B. Shattuck ◽  
J. Clarke
Keyword(s):  
Room Temperature ◽  
Rapid Freezing ◽  
Cryogenic Temperatures ◽  
Soft Or ◽  
Electrically Conductive ◽  
Force Microscopy ◽  
Flexible Molecules ◽  
Advantages And Disadvantages ◽  
Atomic Force ◽  
Chemical Perturbation

The atomic force microscope (AFM) is capable of imaging electrically conductive and non-conductive surfaces at atomic resolution. When used to image biological samples, however, lateral resolution is often limited to nanometer levels, due primarily to AFM tip/sample interactions. Several approaches to immobilize and stabilize soft or flexible molecules for AFM have been examined, notably, tethering coating, and freezing. Although each approach has its advantages and disadvantages, rapid freezing techniques have the special advantage of avoiding chemical perturbation, and minimizing physical disruption of the sample. Scanning with an AFM at cryogenic temperatures has the potential to image frozen biomolecules at high resolution. We have constructed a force microscope capable of operating immersed in liquid n-pentane and have tested its performance at room temperature with carbon and metal-coated samples, and at 143° K with uncoated ferritin and purple membrane (PM).

Planar defects in ordered (Ga,In)P

1988 ◽  
Vol 46 ◽  
pp. 902-903
Author(s):  
S. McKernan ◽  
C. B. Carter ◽  
D. Bour ◽  
J. R. Shealy
Keyword(s):  
Electron Diffraction ◽  
Vapor Phase ◽  
Growth Direction ◽  
High Density ◽  
Ordered Structure ◽  
Planar Defects ◽  
Diffraction Patterns ◽  
Ternary Semiconductors ◽  
Anion Species ◽  
Metallic Vapor

The growth of ternary III-V semiconductors by organo-metallic vapor phase epitaxy (OMVPE) is widely practiced. It has been generally assumed that the resulting structure is the same as that of the corresponding binary semiconductors, but with the two different cation or anion species randomly distributed on their appropriate sublattice sites. Recently several different ternary semiconductors including AlxGa1-xAs, Gaxln-1-xAs and Gaxln1-xP1-6 have been observed in ordered states. A common feature of these ordered compounds is that they contain a relatively high density of defects. This is evident in electron diffraction patterns from these materials where streaks, which are typically parallel to the growth direction, are associated with the extra reflections arising from the ordering. However, where the (Ga,ln)P epilayer is reasonably well ordered the streaking is extremely faint, and the intensity of the ordered spot at 1/2(111) is much greater than that at 1/2(111). In these cases it is possible to image relatively clearly many of the defects found in the ordered structure.

A conduction-cooled stage for high-resolution Cryo-SEM

1992 ◽  
Vol 50 (2) ◽  
pp. 1282-1283
Author(s):  
John G. Sheehan
Keyword(s):  
High Resolution ◽  
Liquid Nitrogen ◽  
Mechanical Stability ◽  
Cooling System ◽  
Cold Trap ◽  
Nitrogen Gas ◽  
Particulate Suspensions ◽  
Advantages And Disadvantages ◽  
Convection Cooling ◽  
Styrene Butadiene

The goal is to examine with high resolution cryo-SEM aqueous particulate suspensions used in coatings for printable paper. A metal-coating chamber for cryo-preparation of such suspensions was described previously. Here, a new conduction-cooling system for the stage and cold-trap in an SEM specimen chamber is described. Its advantages and disadvantages are compared to a convection-cooling system made by Hexland (model CT1000A) and its mechanical stability is demonstrated by examining a sample of styrene-butadiene latex.In recent high resolution cryo-SEM, some stages are cooled by conduction, others by convection. In the latter, heat is convected from the specimen stage by cold nitrogen gas from a liquid-nitrogen cooled evaporative heat exchanger. The advantage is the fast cooling: the Hexland CT1000A cools the stage from ambient temperature to 88 K in about 20 min. However it consumes huge amounts of liquid-nitrogen and nitrogen gas: about 1 ℓ/h of liquid-nitrogen and 400 gm/h of nitrogen gas. Its liquid-nitrogen vessel must be re-filled at least every 40 min.

Computer simulations for the TEM bend contour technique

1996 ◽  
Vol 54 ◽  
pp. 134-135
Author(s):  
Vladimir Yu. Kolosov ◽  
Anders R. Thölén
Keyword(s):  
Computer Simulations ◽  
Real Space ◽  
Advantages And Disadvantages ◽  
Short Overview ◽  
Diffraction Contrast ◽  
Beam Method ◽  
Convergent Beam ◽  
Contour Technique

In this paper we give a short overview of two TEM applications utilizing the extinction bend contour technique (BC) giving the advantages and disadvantages; especially we consider two areas in which the BC technique remains unique. Special attention is given to an approach including computer simulations of TEM micrographs.BC patterns are often observed in TEM studies but are rarely exploited in a serious way. However, this type of diffraction contrast was one of the first to be used for analysis of imperfections in crystalline foils, but since then only some groups have utilized the BC technique. The most extensive studies were performed by Steeds, Eades and colleagues. They were the first to demonstrate the unique possibilities of the BC method and named it real space crystallography, which developed later into the somewhat similar but more powerful convergent beam method. Maybe, due to the difficulties in analysis, BCs have seldom been used in TEM, and then mainly to visualize different imperfections and transformations.

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