The Synthesis of Maghemite and Hematite (γ-Fe2O3, α-Fe2O3) Nanospheres

2007 ◽  
Vol 534-536 ◽  
pp. 157-160 ◽  
Author(s):  
M.A. Dar ◽  
S.G. Ansari ◽  
Rizwan Wahab ◽  
Young Soon Kim ◽  
Hyung Shik Shin
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Iron Oxide ◽  
Pore Size ◽  
Field Emission ◽  
Sol Gel ◽  
Oxide Powder ◽  
Transmission Electron ◽  
Scanning Electron

Maghemite and hematite nanospheres were synthesized by using the Sol-gel technique. The structural properties of these nanosphere powders were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM),and pore size distribution.Hematite phase shows crystalline structures.The mean particle size that resulted from BET and XRD analyses were 4.9 nm and 2 nm. The field emission scanning electron microscopy shows iron-oxide powder is composed of nanosized particles, but in nanosized aggregates (agglomeration of particles). It can be seen from transmission electron microscopy that the size of the particles are very small which is in good agreement with the FESEM and the Xray diffraction. TEM and FESEM confirmed that the iron-oxide powder is composed of sizes from 8 nm to 10 nm. The BET and pore size method were employed for specific surface area determination.

Synthesis of Iron Oxide Nanowires by Heating Iron Foils

2007 ◽  
Vol 342-343 ◽  
pp. 597-600
Author(s):  
Hyoun Woo Kim ◽  
S.H. Shim ◽  
B.H. O ◽  
S.G. Lee ◽  
S.G. Park ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Iron Oxide ◽  
Diffraction Pattern ◽  
Growth Mechanisms ◽  
Oxide Nanowires ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Electron

We have fabricated the iron oxide nanowires directly from iron foils through the simple heating in N2 ambient. We have characterized the samples by means of scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray (EDX) spectroscopy, and selected area diffraction pattern. The EDX spectrum revealed that the nanowires contained elements of Fe and O. The iron oxide nanowires were crystalline with diameters in the range of 30-200 nm. We have discussed the possible growth mechanisms.

Nanostructured CaWO4, CaWO4:Eu3+ and CaWO4:Tb3+ Particles: Sonochemical Synthesis and Luminescent Properties

2008 ◽  
Vol 8 (3) ◽  
pp. 1183-1190 ◽  
Author(s):  
Chunxia Li ◽  
Cuikun Lin ◽  
Xiaoming Liu ◽  
Jun Lin
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Field Emission ◽  
Spherical Particles ◽  
X Ray Diffraction ◽  
Blue Emission Band ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Electron

Nanostructured CaWO4, CaWO4:Eu3+, and CaWO4:Tb3+ phosphor particles were synthesized via a facile sonochemical route. X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, photoluminescence, low voltage cathodoluminescence spectra, and photoluminescence lifetimes were used to characterize the as-obtained samples. The X-ray diffraction results indicate that the samples are well crystallized with the scheelite structure of CaWO4. The transmission electron microscopy and field emission scanning electron microscopy images illustrate that the powders consist of spherical particles with sizes from 120 to 160 nm, which are the aggregates of even smaller nanoparticles ranging from 10 to 20 nm. Under UV light or electron beam excitation, the CaWO4 powder exhibited a blue emission band with a maximum at 430 nm originating from the WO2−4 groups, while the CaWO4:Eu3+ powder showed red emission dominated by 613 nm ascribed to the 5D0 → 7F2 of Eu3+, and the CaWO4:Tb3+ powders showed emission at 544 nm, ascribed to the 5D4 → 7F5 transition of Tb3+. The PL excitation and emission spectra suggest that the energy is transferred from WO2−4 to Eu3+CaWO4:Eu3+ and to Tb3+ in CaWO4:Tb3+. Moreover, the energy transfer from WO2−4 to Tb3+ in CaWO4:Tb3+ is more efficient than that from WO2−4 to Eu3+ in CaWO4:Eu3+. This novel and efficient pathway could open new opportunities for further investigating the novel properties of tungstate materials.

Effects of Lichens on Uranium Migration

2000 ◽  
Vol 663 ◽  
Author(s):  
Takeshi Kasama ◽  
Takashi Murakami ◽  
Toshihiko Ohnuki ◽  
O. William Purvis
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Field Emission ◽  
Physiological Processes ◽  
Transmission Electron ◽  
Uranium Migration ◽  
Uranium Minerals ◽  
Spoil Heaps ◽  
Scanning Electron

ABSTRACTThe lichenTrapelia involutafrom uraniferous spoil heaps in Cornwall, England, growing directly on the secondary uranium minerals, metazeunerite and metatorbernite, was examined by field-emission scanning electron microscopy and transmission electron microscopy to assess the effect ofTrapeliaon uranium migration. We observed metazeunerite, sericite and scorodite as well as unidentified Fe-, Pb/As-, Fe/As-, Al/P-, Pb-bearing minerals concentrated in the lichen exciple and medulla. In addition, metazeunerite also occurred in the epithecium. The chemistries, sizes, and occurrences of the above minerals in the lichen suggest that fixation of U as well as Pb, As, Fe, and Al is dependent on lichen physiological processes. We suggestTrapeliaaccumulates these elements from groundwater and precipitates the above minerals within specific tissues. Our results indicate that some lichens retard uranium migration by accumulating uranium from groundwater and forming uranium-bearing minerals within their tissues.

scholarly journals Effect of Sintering Temperatures on the Synthesis of SnO2 Nanospheres

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Bharat G. Pawar ◽  
Dipak V. Pinjari ◽  
Sanjay S. Kolekar ◽  
Aniruddha B. Pandit ◽  
Sung H. Han
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Large Scale ◽  
Sol Gel ◽  
Visible Region ◽  
Optoelectronic Devices ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Electron

In this communication we report the rapid nanostructure of SnO2 with a spherical morphology which has been prepared in large scale via sol-gel method. The products were characterized with scanning electron microscopy, X-ray powder diffraction, transmission electron microscopy, FTIR, and photoluminescence spectroscopy. The strong photoluminescence of the nanosphere in visible region suggested possible application in nanoscaled optoelectronic devices. A possible growth mechanism for the SnO2 nanosphere in terms of solvation, hydrolysis, and polymerization was proposed.

THE ADVANTAGE OF LOW GROWTH TEMPERATURE AND V/III RATIO FOR InxGa1-xAs NANOWIRES GROWTH

NANO ◽  
2011 ◽  
Vol 06 (02) ◽  
pp. 159-165 ◽  
Author(s):  
EDY WIBOWO ◽  
ZULKAFLI OTHAMAN ◽  
SAMSUDI SAKRANI ◽  
IMAM SUMPONO
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Chemical Composition ◽  
Field Emission ◽  
Growth Temperature ◽  
X Ray ◽  
Transmission Electron ◽  
Nanowires Growth ◽  
Scanning Electron

Cylindrical In x Ga 1-x As nanowires (NWs) perpendicular to the substrate have been successfully grown using MOCVD. Morphology of In x Ga 1-x As NWs has been observed using Field Emission-Scanning Electron Microscopy (FE-SEM) and Transmission Electron Microscopy (TEM). Both FE-SEM and TEM results show that the NWs grown at low growth temperature and V/III ratio were via direct impinging mechanism. Energy Dispersive X-ray spectroscopy (EDX) results confirm that the cylindrical NWs grown via direct impinging mechanism and tends to have uniform chemical composition.

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