Solution Synthesis and Photoluminescence Studies of Small Crystallites of Cadmium Telluride

1992 ◽  
Vol 272 ◽  
Author(s):  
Robert F. Jarvis ◽  
Matthias Müllenborn ◽  
Ben G. Yacobi ◽  
Nancy M. Haegel ◽  
Richard B. Kaner
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Quantum Confinement ◽  
Blue Shift ◽  
Synthetic Method ◽  
Processing Conditions ◽  
Solution Synthesis ◽  
Transmission Electron ◽  
Crystallite Sizes ◽  
Photoluminescence Studies

ABSTRACTSmall crystallites of CdTe have been produced using a new solution synthetic method. In this technique, Cdl2 and Na2Te are each dissolved separately in methanol before rapid mixing. The product of this reaction is pure, stoichiometric CdTe with interesting electronic and optical properties. Photoluminescence studies of this material show a blue shift due to the quantum confinement, indicating the presence of small crystallites. Transmission electron microscopy confirms the presence of nanocrystals. Reaction temperature and processing conditions can be varied to change the crystallite sizes produced. This synthesis can also produce nanocrystalline HgTe.

A STUDY ON A NEW SYNTHETIC METHOD OF CdS AND CdSe NANOPARTICLES AND THEIR ORGANIC/INORGANIC NANOCOMPOSITE

2002 ◽  
Vol 01 (05n06) ◽  
pp. 501-505 ◽  
Author(s):  
JU YOUNG LEE ◽  
YOUNG SOO KANG ◽  
YONG JOO KIM
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Particle Size ◽  
Cdse Nanoparticles ◽  
Inorganic Nanoparticles ◽  
Synthetic Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Inorganic Films

Materials such as CdS and CdSe inorganic nanoparticles have photoluminescence. Sodium oleate has been used as effective stabilizers for the synthesis of CdS and CdSe nanoparticles in water by autoclave method. Photoluminescence of CdS and CdSe with particle size of 5–14 nm showed λ max at 520 nm and 600 nm, respectively, when were excited at 365 nm. These nanoparticles doped into the PVA resulted in the organic/inorganic films ( PVA/CdS , CdSe ). Photoluminescence, X-ray diffraction and transmission electron microscopy were employed for their characterization.

The Flocculation and Stability of TiO2 Nanoparticles

2012 ◽  
Vol 548 ◽  
pp. 138-142
Author(s):  
Xiao Ying Liu ◽  
Xiao Dong Hao ◽  
Chun Xiang Gu ◽  
Yu Xin Zhang ◽  
Xin Lu Li ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Digital Camera ◽  
Processing Conditions ◽  
X Ray Diffraction ◽  
Thermogravimetric Method ◽  
X Ray ◽  
Transmission Electron ◽  
Potential Applications ◽  
Solvent Washing

In this work, TiO2nanoparticles (NPs) were prepared through a well-developed hydrothermal method. The dry products were characterized by digital camera, transmission electron microscopy (TEM), X-ray diffraction (XRD) and thermogravimetric method (TGA). These results suggested that TiO2NPs were well-crystallized and oleic acid-capped (OA-capped; 33.42 wt.%). In order to investigate the flocculation and stability of TiO2NPs colloids, redispersed experiments were carried out by altering the preparative parameters (e.g., redispersion solvent, washing times). In addition, the compounding stability of TiO2NPs colloids with AuNPs colloids and MnO4-solution under processing conditions (e.g., aging with stirring and under UV irradiation) were also studied. In principle, systematic investigations of flocculation and stability of TiO2NPs will be useful for their potential applications including novel photocatalysts and biosensors.

Cantilever Epitaxy of GaN on Sapphire: Further Reductions in Dislocation Density

2002 ◽  
Vol 743 ◽  
Author(s):  
D. M. Follstaedt ◽  
P. P. Provencio ◽  
D. D. Koleske ◽  
C. C. Mitchell ◽  
A. A. Allerman ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Dislocation Density ◽  
Threading Dislocation ◽  
Threading Dislocations ◽  
Processing Conditions ◽  
Optimum Growth ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Threading Dislocation Density

ABSTRACTThe density of vertical threading dislocations at the surface of GaN grown on sapphire by cantilever epitaxy has been reduced with two new approaches. First, narrow mesas (<1 μm wide) were used and {11–22} facets formed over them early in growth to redirect dislocations from vertical to horizontal. Cross-sectional transmission electron microscopy was used to demonstrate this redirection and to identify optimum growth and processing conditions. Second, a GaN nuc-leation layer with delayed 3D → 2D growth transition and inherently lower threading dislocation density was adapted to cantilever epitaxy. Several techniques show that a dislocation density of only 2–3×107/cm2 was achieved by combining these two approaches. We also suggest other developments of cantilever epitaxy for reducing dislocations in heteroepitaxial systems.

Vapor Deposited Ag2S Films as High Resolution Photoregistering Materials in The Infrared Region

1993 ◽  
Vol 334 ◽  
Author(s):  
J. Eneva ◽  
S. Kitova ◽  
A Panov ◽  
H. Haefke
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Chemical Composition ◽  
High Resolution ◽  
Electron Diffraction ◽  
Narrow Band ◽  
Stoichiometric Composition ◽  
Infrared Region ◽  
Processing Conditions ◽  
Transmission Electron

AbstractAg2S as a narrow band gap semiconductor is appropriate for photoimaging in the infrared (IR) region. Co-evaporation of Ag and S from two separate sources was used for preparing of thin Ag2S films with different Ag/S ratio. Gelatine subbed glass plates were used as substrates. The structure of the films obtained was examined by transmission electron microscopy and electron diffraction. The effects of chemical composition, film thickness and processing conditions on the photographic parameters were studied.It is shown that after appropriate processing thin Ag2S films with stoichiometric composition can. be successfully used as high resolution (1600 lines/mm) photographic materials in the IR region.

Laser ablation of nanoparticles and nanoparticulate, thick Fe1.92Tb0.3Dy0.7 films

2010 ◽  
Vol 25 (9) ◽  
pp. 1733-1740 ◽  
Author(s):  
J. Ma ◽  
M.F. Becker ◽  
J.W. Keto ◽  
D. Kovar
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Laser Ablation ◽  
Processing Parameters ◽  
Processing Conditions ◽  
Transmission Electron ◽  
Resistance To Oxidation ◽  
Mean Size ◽  
Scanning Electron

Two laser processes, flat plate ablation (FPA) and laser ablation of microparticle aerosols (LAMA), capable of producing nanoparticles and nanoparticulate thick films of Terfenol-D (Fe1.92Tb0.3Dy0.7) were investigated. The influence of processing parameters on the sizes, compositions, and morphologies of the nanoparticles produced using these processes were studied by transmission electron microscopy. The nanoparticles were used to deposit nanoparticulate films by supersonic impaction with thicknesses ranging from 4 to 50 μm, depending on processing conditions. The microstructures and properties of the films were studied using scanning electron microscopy and magnetometry. The LAMA process produced nanoparticles with a mean size and standard deviation (SD) of 8 to 10 nm ± 5 nm, depending on the type of gas used during synthesis. In contrast, nanoparticles produced using the FPA process exhibited a much broader size distribution varying from 5 to 150 nm and a much greater variation in compositions compared to the LAMA process. Films produced using LAMA also had lower levels of porosity compared to those produced using FPA as a result of the smaller, more uniform nanoparticles from which they were produced and the resulting higher impaction velocities. Compared to the FPA-produced films, the LAMA-produced films exhibited greater resistance to oxidation, higher magnetizations (13–15 emu/g versus 9–11 emu/g, depending on processing conditions) and lower coercivities (versus 41–59 Oe versus 80–110 Oe).

The Structure of Nb Obtained by Severe Plastic Deformation and its Thermal Stability

2010 ◽  
Vol 667-669 ◽  
pp. 409-414 ◽  
Author(s):  
Vladimir V. Popov ◽  
E.N. Popova ◽  
A.V. Stolbovsky ◽  
V.P. Pilyugin
Keyword(s):  
Electron Microscopy ◽  
Thermal Stability ◽  
Transmission Electron Microscopy ◽  
Plastic Deformation ◽  
High Pressure Torsion ◽  
Nanocrystalline Structure ◽  
Transmission Electron ◽  
Crystallite Sizes ◽  
Evolution Of Structure ◽  
Thermal Stability Of

Evolution of structure of Nb subjected to high-pressure torsion (HPT) with various strain at cryogenic and room temperatures and further annealing in the temperature range of 100-7000C has been studied by transmission electron microscopy (TEM) and microhardness measurements. HPT in liquid nitrogen enables to obtain true nanocrystalline structure with crystallite sizes of about 75 nm and the record-breaking microhardness of 4800 MPa. The thermal stability of the structure obtained is analysed.

Optical properties of porous silicon

1992 ◽  
Vol 70 (10-11) ◽  
pp. 1184-1193 ◽  
Author(s):  
D. J. Lockwood ◽  
G. C. Aers ◽  
L. B. Allard ◽  
B. Bryskiewicz ◽  
S. Charbonneau ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Quantum Confinement ◽  
Chemical Dissolution ◽  
Optical Absorption Spectra ◽  
Porous Si ◽  
Transmission Electron ◽  
Amorphous Si ◽  
Si Nanostructures ◽  
Si Films

The optical and structural properties of porous Si films produced by electrochemical and chemical dissolution of Si have been studied by a variety of techniques. Raman scattering and transmission electron microscopy have shown the samples to contain crystalline Si wires and (or) spherites 3–8 nm in diameter and (or) amorphous Si. The optical absorption spectra and the wavelength, temperature, and lifetime dependence of the photoluminescence obtained from most of the samples are entirely consistent with the quantum confinement of excitons in Si nanostructures. Quite different photoluminescence was obtained from other samples composed only of amorphous Si, and this is attributed to the presence of silicon oxyhydride species.

Deposition of zinc sulfide quantum dots from a single-source molecular precursor

1999 ◽  
Vol 14 (8) ◽  
pp. 3237-3240 ◽  
Author(s):  
N. Revaprasadu ◽  
M. Azad Malik ◽  
P. O'Brien ◽  
G. Wakefield
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Bulk Material ◽  
Blue Shift ◽  
Single Source ◽  
Infrared Band ◽  
Zinc Blend ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron

Nanoparticles of ZnS capped with tri-n-octylphosphineoxide (TOPO) and close to monodispersed have been prepared by a single-source route using ethyl(di-ethyldithiocarbamato)zinc(II) as a precursor. The nanoparticles obtained showed quantum size effects in their optical spectra, and the photoluminescence spectrum showed a broad emission that could be attributed to the surface traps. A blue shift of 0.31 eV in relation to the bulk material was observed. The selected area electron diffraction, x-ray diffraction pattern and transmission electron microscopy showed the material to be of the zinc blend structure. The crystallinity of the material was also evident from high-resolution transmission electron microscopy, which gave well-defined images of nano-sized particles with clear lattice fringes and a spacing of approximately 3 Å, corresponding to the (111) planes of the cubic crystalline ZnS phase and in the size range of 3.9–4.9 nm. The presence of strong phosphorus peak in the energy dispersion analytical x-ray pattern, together with a shift in infrared band for P = O of TOPO showed that the particles were TOPO capped.

Structure and Magnetic Properties of Fe-Doped TiO2 Nano-Crystals by Nonaqueous Synthesis

2010 ◽  
Vol 663-665 ◽  
pp. 883-889
Author(s):  
Chu Feng Li ◽  
Ling Yue ◽  
Wen Jin ◽  
Ting Zhang ◽  
Huan Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Anatase Phase ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
X Ray ◽  
Transmission Electron ◽  
Crystallite Sizes ◽  
Nonaqueous Synthesis

Ti1-xFexO2 nanocrystals with x = 0.01, 0.02, 0.03 were prepared via a nonaqueous synthesis route. X-ray diffraction, transmission electron microscopy and high resolution transmission electron microscopy characterization confirmed the formation of anatase-phase nanocrystals with the average crystallite sizes of around 10 nm. The lattice constants alternate with the increase of the Fe content and no iron clusters were generated. X-ray photoelectron spectroscopy measurements showed that the substitutional Fe ions present mainly the valence of +3. The magnetic hysteresis loops measured at room temperature (RT) 300K showed that all the doped samples are atypically ferromagnetic, and the coercivity (Hc) of all the Fe-doping samples is around 0.1 T. An interpretation for the intrinsic RT ferromagnetism is put up based on the free carriers and defects induced interaction between Fe3+ ions.

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