Sonochemical Fabrication and Characterization of Ceria (CeO2) Nanowires

2006 ◽  
Vol 6 (1) ◽  
pp. 157-161 ◽  
Author(s):  
Hong-Liang Chen ◽  
Hai-Yang Zhu ◽  
Hui Wang ◽  
Lin Dong ◽  
Jun-Jie Zhu
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Microstructural Analysis ◽  
Specific Effect ◽  
Ambient Air ◽  
Growth Direction ◽  
Alkali Concentration ◽  
Sonochemical Method ◽  
Visible Absorption ◽  
Transmission Electron

Ceria (CeO2) nanowires have been successfully synthesized by a sonochemical method in ambient air and alkali aqueous solution from CeO2 nanoparticles without using any templates. The results showed that both alkali concentration and ultrasonic irradiation played critical roles in the formation of the nanowires. The crystalline structure and dimensions of the nanowires were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED). The UV-visible absorption spectrum result showed that the products had conspicuous shape-specific effect. Microstructural analysis in HRTEM revealed that the preferential growth direction of CeO2 nanowires was [110]. Moreover, the catalytic activity of Au/CeO2 using CeO2 nanowires as support for CO conversion was higher than that obtained using bulk CeO2 as support.

Microstructural Analysis of SiO2-Al2O3 Glasses

1982 ◽  
Vol 40 ◽  
pp. 562-563
Author(s):  
C. M. Jantzen ◽  
D. G. Howitt
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Microstructural Analysis ◽  
Liquid Immiscibility ◽  
Metastable Region ◽  
Transmission Electron ◽  
Liquidus Temperatures

The mullite-SiO2 liquidus has been extensively studied, and it has been shown that the flattening of the liquidus is related to the existence of a metastable region of liquid immiscibility at sub-liquidus temperatures which is detectable by transmission electron microscopy (TEM) (Fig. 1).

Synthesis and Characterizations of Nanocubes, Monodispersed Nanocrystals and Nanospheres of Au

2007 ◽  
Vol 353-358 ◽  
pp. 2163-2166
Author(s):  
Ming Yang ◽  
Guo Qing Zhou ◽  
Jiang Guo Zhao ◽  
Zhan Jun Li
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Powder Diffraction ◽  
Visible Absorption ◽  
X Ray ◽  
Transmission Electron ◽  
Uv Visible ◽  
Scherrer Formula ◽  
Visible Absorption Spectroscopy

Nanocubes, monodispersed nanocrystals and nanospheres of Au have been prepared by a simple reaction between HAuCl4·4H2O, NaOH and NH2OH·HCl in the presence of gelatin. The role of gelatin and the affection of pH in producing the nanoparticles of Au were discussed. The products were characterized by X-ray powder diffraction, transmission electron microscopy, and UV-visible absorption spectroscopy. The sizes of the monodispersed nanocrystals of Au were estimated by Debye-Scherrer formula according to XRD spectrum.

AQUEOUS SYNTHESIS OF HIGH QUANTUM YIELD AND MONODISPERSED THIOL-CAPPED CdxZn1-xTe QUANTUM DOTS BASED ON ELECTROCHEMICAL METHOD

NANO ◽  
2012 ◽  
Vol 07 (02) ◽  
pp. 1250011 ◽  
Author(s):  
JUNWEI LI ◽  
YANG JIANG ◽  
YUGANG ZHANG ◽  
DI WU ◽  
ANQI LUO ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Quantum Dots ◽  
Quantum Yield ◽  
Electrochemical Method ◽  
Large Scale ◽  
Ostwald Ripening ◽  
Visible Absorption ◽  
Aqueous Synthesis ◽  
Transmission Electron

A facile green approach has been developed to control the growth regime in the aqueous synthesis of CdxZn1-xTe semiconductor quantum dots (QDs) based on the electrochemistry method. The Low growth temperature and slow injection of Te precursor are used to prolong the diffusion controlled stage and thus suppress Ostwald ripening during the nanocrystal growth. The experimental results showed that a low concentration of Te precursor will definitely influence the growth procedure. The UV–visible absorption spectra, as well as transmission electron microscopy (TEM) shows the QDs a good monodispersity at any interval of the reaction procedure. The high-resolution transmission electron microscopy (HRTEM) images and powder X-ray diffraction (XRD) pattern suggested that the as-prepared QDs have high crystallinity and cubic structure. The size and composition-dependent fluorescent emission wavelength of the resultant CdxZn1-xTe alloyed QDs can be tuned from 460 to 610 nm, and their photoluminescent quantum yield can reach up to 70%. Especially in the wavelength range of 510–578 nm, the overall PL QYs of the as-prepared CdxZn1-xTe QDs were above 50%. The current work suggests that electrochemical method is an attractive approach to the synthesis of high-quality II-VI ternary alloyed semiconductor QDs at large-scale with a prominent cost advantage.

Microstructures and Growth Characteristics of Self-Assembled InAs/GaAs Quantum Dots Investigated by Transmission Electron Microscopy

2007 ◽  
Vol 26-28 ◽  
pp. 1207-1210
Author(s):  
Hyung Seok Kim ◽  
Ju Hyung Suh ◽  
Chan Gyung Park ◽  
Sang Jun Lee ◽  
Sam Kyu Noh ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Quantum Dots ◽  
Chemical Potential ◽  
Early Stage ◽  
Compressive Strain ◽  
Potential Gradient ◽  
Growth Direction ◽  
Transmission Electron ◽  
Self Assembled

The microstructure and strain characteristics of self-assembled InAs/GaAs quantum dots (QDs) were studied by using transmission electron microscopy. Compressive strain was induced to uncapped QDs from GaAs substrate and the misfit strain largely increased after the deposition of GaAs cap layer. Tensile strain outside QD was extended along the vertical growth direction; up to 15 nm above the wetting layer. Vertically nonaligned and aligned stacked QDs were grown by adjusting the thickness of GaAs spacer layers. The QDs with a lens-shaped morphology were formed in the early stage of growth, and their apex was flattened by the out-diffusion of In atoms upon GaAs capping. However, aligned QDs maintained their lens-shaped structure with round apex after capping. It is believed that their apex did not flatten because the chemical potential gradient of In was relatively low due to the adjacent InAs QD layers.

SiC NWs Grown on Silicon Substrate Using Fe as Catalyst

2014 ◽  
Vol 806 ◽  
pp. 39-42
Author(s):  
Paola Lagonegro ◽  
Matteo Bosi ◽  
Giovanni Attolini ◽  
Marco Negri ◽  
Sathish Chander Dhanabalan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Growth Temperature ◽  
Silicon Substrate ◽  
Growth Direction ◽  
Carrier Gas ◽  
Sic Nanowires ◽  
Transmission Electron

We report on the synthesis of SiC nanowires (NWs) using iron as catalyst. The NWs were grown on silicon substrate by vapour-liquid-solid (VLS) mechanism with propane and silane as precursors, both 3% diluted in hydrogen, and hydrogen as carrier gas. The growth temperature was 1250°C, to reach the eutectic values of the Si-Fe alloy and to permit the VLS mechanism. The as-grown SiC nanowires were characterized by scanning and transmission electron microscopy. The nanowires are from 30 to 100 nm in diameter and several μm in length, with <111> growth direction.

Characterization and their Fluorescence of Fe3+-Doped La2Zr2O7 Nanocrystals by a Salt-Assistant Combustion Method

2011 ◽  
Vol 306-307 ◽  
pp. 1257-1261 ◽  
Author(s):  
Yun Shan Bai ◽  
Lu De Lu ◽  
Jian Chun Bao
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Solid Solutions ◽  
Low Cost ◽  
Combustion Process ◽  
Combustion Method ◽  
Crystal Form ◽  
X Ray Diffraction ◽  
Visible Absorption ◽  
Transmission Electron

Nanocrystalline Fe3+-doped La2Zr2O7 series solid solutions were prepared by a convenient salt-assisted combustion process using glycine as fuel. The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The results showed the La ion can be partially replaced by Fe ion. The partial substituted products were still single-phase solid solutions and the crystal form remained unchanged. TEM images reveal that the products are composed of well-dispersed square-shaped nanocrystals. The method provides a convenient and low-cost route for the synthesis of nanostructures of oxide materials. The fluorescence of La1.8Fe0.2Zr2O7 nanocrystals was evaluated by the UV-visible absorption spectra and the fluorescence spectra. The results indicate that (LaxFe1-x)2Zr2O7 nanocrystals prepared by this method are a kind of potential fluorescent-emitted material.

Scanning Transmission Electron Microscopy Studies of the Microstructure of High Chromium Steel after Long Time Exposure

2013 ◽  
Vol 212 ◽  
pp. 25-28 ◽  
Author(s):  
Kinga B. Rodak ◽  
Adam Hernas
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Scanning Transmission Electron Microscopy ◽  
Microstructural Analysis ◽  
Chromium Steel ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Δ Ferrite ◽  
Scanning Transmission ◽  
Long Time

The detailed microstructural analysis of HCM12 steel after long time (100 000 hours) exposure at service temperatures around 600°C was investigated by means of scanning transmission electron microscopy. The results show, that the recovery processes of the martensite lath structure and δ ferrite are significantly different. Moreover are differences in particles precipitating at the martensite and δ ferrite. The intensive process intragranular M23C6 and Laves particles precipitating is observed at the martensite/ δ ferrite interfaces.

Microstructural analysis of high-pressure compressed C60

2001 ◽  
Vol 16 (7) ◽  
pp. 1960-1966 ◽  
Author(s):  
K. Miyazawa ◽  
H. Satsuki ◽  
M. Kuwabara ◽  
M. Akaishi
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Pressure ◽  
High Resolution ◽  
Microstructural Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Hardness Tests ◽  
Lattice Planes

The structure and hardness of C60 bulk specimens compressed under 5.5 GPa at room temperature to 600 °C are investigated by high-resolution transmission electron microscopy, x-ray diffraction, and micro-Vickers hardness tests. A strong accumulation of the [1 1 0]tr orientation of high-pressure-treated C60 specimens was developed along the compression axis, and stacking faults and nano-sized deformation twins were introduced into the C60 specimens compressed at 450–600 °C. Curved lattice planes indicating a polymerization of C60 were observed by high resolution transmission electron microscopy (HRTEM). The polymerization of the high-pressure-compressed C60 is also supported by the computer simulation of HRTEM images.

Novel Zn-Doped SnO2 Hierarchical Architectures: Facile Synthesis, Structural Characterization and Enhanced Photocatalytic Property

2012 ◽  
Vol 512-515 ◽  
pp. 334-338 ◽  
Author(s):  
Tie Kun Jia ◽  
Fan Zhang ◽  
Xiao Feng Wang ◽  
Wei Min Wang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Photocatalytic Activity ◽  
Mixed Solvents ◽  
Photocatalytic Property ◽  
Growth Direction ◽  
High Photocatalytic Activity ◽  
Transmission Electron ◽  
Preferential Growth Direction ◽  
Hierarchical Architectures

Zn-doped SnO2 seaflower like hierarchical architectures have been synthesized via a solvothermal synthesis route in the mixed solvents of ethanol and deionized water. The observations of field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) showed that Zn-doped SnO2 seaflower like hierarchical architectures were assembled by the nanowires. The preferential growth direction of nanowires was determined based on the analysis of high resolution transmission electron microscopy (HRTEM). The products were also characterized by X-ray diffraction (XRD) and X-photoelectron spectrum (XPS), and the results indicated that Sn4+ ions were successfully substituted by Zn2+. The photocatalytic activity of Zn-doped SnO2 seaflower like hierarchical architectures was evaluated by the degradation of RhB aqueous solution and the results showed that the product had high photocatalytic activity efficiency.

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