scholarly journals Oxidation of MBE-Grown ZnTe and ZnTe/Zn Nanowires and Their Structural Properties

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5252
Author(s):  
Katarzyna Gas ◽  
Slawomir Kret ◽  
Wojciech Zaleszczyk ◽  
Eliana Kamińska ◽  
Maciej Sawicki ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Elevated Temperatures ◽  
Atmospheric Conditions ◽  
Zno Nanocrystals ◽  
Transmission Electron ◽  
Before And After ◽  
Fine Crystalline Structure ◽  
And Performance ◽  
Comparative Structural Characterization

Results of comparative structural characterization of bare and Zn-covered ZnTe nanowires (NWs) before and after thermal oxidation at 300 °C are presented. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, and Raman scattering not only unambiguously confirm the conversion of the outer layer of the NWs into ZnO, but also demonstrate the influence of the oxidation process on the structure of the inner part of the NWs. Our study shows that the morphology of the resulting ZnO can be improved by the deposition of thin Zn shells on the bare ZnTe NWs prior to the oxidation. The oxidation of bare ZnTe NWs results in the formation of separated ZnO nanocrystals which decorate crystalline Te cores of the NWs. In the case of Zn-covered NWs, uniform ZnO shells are formed, however they are of a fine-crystalline structure or partially amorphous. Our study provides an important insight into the details of the oxidation processes of ZnTe nanostructures, which could be of importance for the preparation and performance of ZnTe based nano-devices operating under normal atmospheric conditions and at elevated temperatures.

A Detailed Interface Characterization of the Explosively Welded Three-Layered Ti Gr 1/Alloy 400/1.4462 Steel Clads Before and After Heat Treatment

2021 ◽  
pp. 1-9
Author(s):  
Marta Janusz-Skuza ◽  
Agnieszka Bigos ◽  
Łukasz Maj ◽  
Jerzy Morgiel ◽  
Marek Faryna ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Hexagonal Phase ◽  
Cubic Phase ◽  
Interface Zone ◽  
Transmission Electron ◽  
Before And After ◽  
Diffusion Phenomena ◽  
Zone Microstructure

The presented research focused on the microstructural characteristics of explosively welded three-layered Ti Grade (Gr) 1/Alloy 400/1.4462 steel clads before and after heat treatment being of large practical potential. Scanning electron microscopy (SEM) analyses have shown that both interfaces formed between the plates are continuous and without defects. The in-depth examination was dedicated to the upper Ti Gr 1/Alloy 400 interface, located closer to the explosive material, therefore, subjected to more extreme welding conditions. The presence of cubic phase Ti2Ni, hexagonal phase Ni3Ti, and tetragonal phase (Cu x Ni1−x)2Ti were confirmed within the melted zones, which slightly widened due to annealing, being an essential step in the manufacturing of these modern materials. Transmission electron microscopy observations in the nano scale confirmed the preliminary chemical composition analyses collected with energy-dispersive X-ray spectroscopy in SEM. They additionally revealed the interface zone microstructure transformation due to the annealing. It was evidenced that initially mixed phases in the form of grains, after heat treatment formed irregular bands arranged in the following sequence: Alloy 400/Ni3Ti/(Cu x Ni1−x)2Ti/Ti2Ni/Ti Gr 1. A clear segregation of Cu and Ni forming two separate layers was also noticed. These diffusion phenomena may influence the strength of the final product, therefore need further studies regarding the prolonged annealing state.

Synthesis and Characterization of Superfine Nanostructure Manganese Dioxide Spontaneously Coated onto Carbon Nanotubes

2011 ◽  
Vol 364 ◽  
pp. 398-401
Author(s):  
Johari Md Salleh ◽  
Aziah Buang Nor ◽  
Muhammad Zamir Othman
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Manganese Dioxide ◽  
Synthesis And Characterization ◽  
X Ray ◽  
Transmission Electron ◽  
Before And After ◽  
Cnts Surface ◽  
Thermal Stability Of

Manganese dioxide nanostructered (MnO2) was coated onto carbon nanotubes (CNTs) by simple immersion of the CNTs into a KMnO4 aqueous solution. The morphology of the CNTs before and after MnO2 deposition was examined using field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM). The superfine coral-like MnO2 deposited and fully covered on the CNTs surface at pH 8. At pH 2 and 6 the MnO2 deposited as the superfine nanorod structure. The superfine MnO2 phase was identified as Birnessite-type MnO2 by X-ray powder diffraction and FESEM. The thermal stability of the superfine nanostructure MnO2 coated CNTs is increase based on the TGA with the weight loss of 4% at 400°C to 900°C.

The Effect of Dopant Additions on the Microstructure of Boron Fibers Before and After Reaction to MgB2

2004 ◽  
Vol 848 ◽  
Author(s):  
James V. Marzik ◽  
Raymond J. Suplinskas ◽  
William J. Croft ◽  
Warren J. MoberlyChan ◽  
John D. DeFouw ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Elevated Temperatures ◽  
Chemical Vapor ◽  
X Ray Diffraction ◽  
X Ray ◽  
Boron Fiber ◽  
Transmission Electron ◽  
Before And After ◽  
Fiber Metal ◽  
Molten Magnesium

ABSTRACTBoron fibers made by a commercial chemical vapor deposition (CVD) process have been used as precursors for the formation of magnesium diboride (MgB2) superconducting wires. Prior to a reaction with magnesium, the addition of dopants such as carbon and titanium to the boron fiber has been shown to enhance the superconducting properties of MgB2. These dopants also influence the kinetics of the reaction with magnesium. In this study, the effect of carbon dopant additions on the microstructure of boron fibers was investigated using powder x-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Additionally, bundles of boron fibers were pressure infiltrated with molten magnesium and reacted at elevated temperatures. The microstructure and microchemistry of the fiber-metal interfaces were investigated by TEM and energy dispersive x-ray analysis (EDS).

An Environmental Transmission Electron Microscope for in situ Synthesis and Characterization of Nanomaterials

2005 ◽  
Vol 20 (7) ◽  
pp. 1695-1707 ◽  
Author(s):  
Renu Sharma
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Elevated Temperatures ◽  
Dark Field ◽  
In Situ Synthesis ◽  
Synthesis And Characterization ◽  
Transmission Electron ◽  
Electron Microscopes

The world of nanomaterials has become the real world for most applications in the area of nanotechnology. As postsynthesis handling of materials at the nanoscale level is impractical, nanomaterials must be synthesized directly as part of a device or circuit. The demands of nanotechnology have led to modifications in the design of transmission electron microscopes (TEMs) that enable in situ synthesis and characterization simultaneously. The environmental TEM (ETEM) is one such modified instrument that has often been used to follow gas–solid and/or liquid–solid interactions at elevated temperatures. Although the history and development of the ETEM, also called the controlled atmosphere or environmental cell TEM, is as old as transmission electron microscopy itself, developments in the design of medium-voltage TEMs have succeeded in bringing resolutions down to the subnanometer level. A modern ETEM equipped with a field-emission gun, energy filter or electron energy-loss spectrometer, scanning transmission electron microscopy coils, and bright-field and dark-field detectors can be a versatile tool for understanding chemical processes at the nanometer level. This article reviews the design and operations of a dedicated ETEM. Its applications range from the in situ characterization of reaction steps, such as oxidation-reduction and hydroxylation, to the in situ synthesis of nanomaterials, such as quantum dots and carbon nanotubes. Some examples of the current and the future applications for the synthesis and characterization of nanomaterials are also discussed.

Microstructural Characterization of Epitaxial Cubic Silicon Carbide Using Transmission Electron Microscopy

2010 ◽  
Vol 645-648 ◽  
pp. 379-382
Author(s):  
Bralee Chayasombat ◽  
Y. Kimata ◽  
T. Kato ◽  
Tomoharu Tokunaga ◽  
Katsuhiro Sasaki ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Silicon Carbide ◽  
Ion Implantation ◽  
Microstructural Characterization ◽  
Transmission Electron ◽  
Before And After ◽  
Bulge Region ◽  
Cubic Silicon Carbide

Microstructures of switch-back epitaxy cubic silicon carbide (3C-SiC) before and after Al ion implantation were investigated by transmission electron microscopy (TEM). Stacking faults aligned along the {111} were observed in 3C-SiC. A surface bulge was observed in some regions and planar defects were observed under the bulge region. After ion implantation of 3C-SiC, defects were observed to be distributed up to a depth approximately 500 nm from the surface.

Atomistic and dynamic structural characterizations in low-dimensional materials: recent applications of in situ transmission electron microscopy

Microscopy ◽  
2019 ◽  
Author(s):  
He Zheng ◽  
Fan Cao ◽  
Ligong Zhao ◽  
Renhui Jiang ◽  
Peili Zhao ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Atomic Scale ◽  
Transmission Electron ◽  
Indispensable Tool ◽  
And Performance ◽  
Low Dimensional ◽  
Low Dimensional Materials

Abstract In situ transmission electron microscopy has achieved remarkable advances for atomic-scale dynamic analysis in low-dimensional materials and become an indispensable tool in view of linking a material’s microstructure to its properties and performance. Here, accompanied with some cutting-edge researches worldwide, we briefly review our recent progress in dynamic atomistic characterization of low-dimensional materials under external mechanical stress, thermal excitations and electrical field. The electron beam irradiation effects in metals and metal oxides are also discussed. We conclude by discussing the likely future developments in this area.

Studies on Al2O3 - ZrO2 Coatings Structure before and after Thermal Treatment

2007 ◽  
Vol 130 ◽  
pp. 297-301 ◽  
Author(s):  
Ludwik Górski ◽  
Andrzej Pawłowski
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Thermal Treatment ◽  
Tetragonal Zirconia ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Ordered Phases ◽  
Before And After ◽  
Fine Crystalline Structure

Phase transitions occurring in the Al2O3-ZrO2 composite as a result of plasma spraying and subsequent coating annealing are described. X-ray diffraction and transmission electron microscopy methods are applied to study these effects. Separate layers of amorphous, nano- and fine-crystalline structure with the columnar crystals areas have been observed. Thermal treatment causes formation of more ordered phases. Effect of partial stabilization of cubic and tetragonal zirconia due to the presence of alumina has been remarked.

Preparation and Characterization of PVP/Fe3O4 Composite Nanofibers

2011 ◽  
Vol 332-334 ◽  
pp. 783-786
Author(s):  
Xin Wang ◽  
Xue Jia Li ◽  
Qing Qing Wang ◽  
Qu Fu Wei
Keyword(s):  
Electron Microscopy ◽  
Composite Nanofibers ◽  
Average Diameter ◽  
Diameter Distribution ◽  
Fe3o4 Nanoparticle ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Nanofiber Diameter ◽  
And Performance

The PVP/Fe3O4 composite nanofibers with different Fe3O4 nanoparticle loading were obtained by electrospinning. The characterization and performance analysis of the composite nanofibers were studied by scanning electron microscopy (SEM), X-Ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and antistatic fabric instrument. The results showed that the average diameter of PVP/Fe3O4 composite nanofibers is smaller than that of pure PVP. At 5wt% Fe3O4 nanoparticle loading, the coefficient of variation CV value was low, while the composite nanofiber diameter distribution was good. Fe3O4 nanoparticles were spherical and had no obvious agglomeration. With increasing Fe3O4 nanoparticle loading, the thermal and antistatic properties of PVP/Fe3O4 composite nanofibers were significantly improved.

Characterization of Ti Alloys Bombarded by keV Deuterium Ions

1992 ◽  
Vol 268 ◽  
Author(s):  
G.P. Chambers ◽  
G. K. Hubler ◽  
J.A. Sprague ◽  
K.S. Grabowski
Keyword(s):  
Electron Microscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ti Alloys ◽  
Transmission Electron ◽  
Before And After ◽  
Current Densities ◽  
Deuterium Gas ◽  
Secondary Ion

ABSTRACTThin Ti films have been bombarded at room temperature with 350–500 eV deuterium ions at current densities up to 0.5 mA/cm2. Analysis using scanning electron microscopy, x-ray diffraction, transmission electron microscopy, and secondary ion mass spectroscopy were carried out before and after bombardment. It was determined that deuterium diffuses rapidly throughout the Ti film, that the films were in a state of high compressive stress, and that the TiD2 phase was formed. No evidence of deuterium gas bubbles was found.

An Electron Microscope Study of Interdiffusion and Compound Formation in Ta-Au Thin Films

1973 ◽  
Vol 31 ◽  
pp. 32-33 ◽  
Author(s):  
T. C. Tisone ◽  
S. Lau
Keyword(s):  
Electron Microscope ◽  
Electron Microscope Study ◽  
Thermally Grown Oxide ◽  
Ion Milling ◽  
Compound Formation ◽  
Technology Application ◽  
Transmission Electron ◽  
Before And After ◽  
Au Thin Films

In a study of the properties of a Ta-Au metallization system for thin film technology application, the interdiffusion between Ta(bcc)-Au, βTa-Au and Ta2M-Au films was studied. Considered here is a discussion of the use of the transmission electron microscope(TEM) in the identification of phases formed and characterization of the film microstructures before and after annealing.The films were deposited by sputtering onto silicon wafers with 5000 Å of thermally grown oxide. The film thicknesses were 2000 Å of Ta and 2000 Å of Au. Samples for TEM observation were prepared by ultrasonically cutting 3mm disks from the wafers. The disks were first chemically etched from the silicon side using a HNO3 :HF(19:5) solution followed by ion milling to perforation of the Au side.

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