Low Temperature Synthesis of Colloidal CdSe Quantum Dots

2007 ◽  
Vol 7 (11) ◽  
pp. 3780-3783 ◽  
Author(s):  
Seongmi Hwang ◽  
Youngmin Choi ◽  
Beyong-Hwan Ryu
Keyword(s):  
Quantum Confinement ◽  
Growth Time ◽  
Cdse Nanocrystals ◽  
Bandgap Energy ◽  
Synthetic Method ◽  
Cdse Quantum Dots ◽  
Low Temperature Synthesis ◽  
Temperature Synthesis ◽  
Transmission Electron ◽  
Octyl Amine

In this study, the CdSe nanocrystals were prepared in phenyl ether and octyl amine to investigate the variations of their size, bandgap energy, and photoluminescence with growth time and temperature. The sizes of the CdSe nanocrystals were measured using High Resolution Transmission Electron Microscopy (HRTEM), and found to be nearly monodisperse for relatively low growth temperature, 130 °C. Their optic properties were characterized by photoluminescence measurements, which showed that the colors of the nanocrystals could be controlled. The bandgap energies of the nanocrystals were calculated theoretically and found to be in accord with quantum confinement theory. This synthetic method requires only a cheap solvent and offers good reproducibility at a lower price.

Low Temperature Synthesis of Colloidal CdSe Quantum Dots

2007 ◽  
Vol 7 (11) ◽  
pp. 3780-3783
Author(s):  
Seongmi Hwang ◽  
Youngmin Choi ◽  
Beyong-Hwan Ryu
Keyword(s):  
Quantum Confinement ◽  
Growth Time ◽  
Cdse Nanocrystals ◽  
Bandgap Energy ◽  
Synthetic Method ◽  
Cdse Quantum Dots ◽  
Low Temperature Synthesis ◽  
Temperature Synthesis ◽  
Transmission Electron ◽  
Octyl Amine

In this study, the CdSe nanocrystals were prepared in phenyl ether and octyl amine to investigate the variations of their size, bandgap energy, and photoluminescence with growth time and temperature. The sizes of the CdSe nanocrystals were measured using High Resolution Transmission Electron Microscopy (HRTEM), and found to be nearly monodisperse for relatively low growth temperature, 130 °C. Their optic properties were characterized by photoluminescence measurements, which showed that the colors of the nanocrystals could be controlled. The bandgap energies of the nanocrystals were calculated theoretically and found to be in accord with quantum confinement theory. This synthetic method requires only a cheap solvent and offers good reproducibility at a lower price.

Low-Temperature Synthesis of Nano-Crystalline ZnTiO3 Powders by Aqueous Sol-Gel Process

2014 ◽  
Vol 543-547 ◽  
pp. 3741-3744
Author(s):  
Quan Jing Mei ◽  
Cong Ying Li ◽  
Jing Dong Guo ◽  
Gui Wang ◽  
Hai Tao Wu
Keyword(s):  
Sol Gel ◽  
Zinc Nitrate ◽  
X Ray Diffraction ◽  
Low Temperature Synthesis ◽  
Temperature Synthesis ◽  
Calcination Process ◽  
X Ray ◽  
Nano Crystalline ◽  
Transmission Electron ◽  
Sol Gel Process

The ecandrewsite-type ZnTiO3was successfully synthesized by the aqueous sol-gel method using TiO2dioxide and zinc nitrate as starting materials instead of expensive organic solvent and metal alkoxides. The as-prepared nanopowders were characterized by X-ray diffraction (XRD), differential thermal analysis (DTA) and transmission electron microscopy (TEM), respectively. The results showed that the calcination process of gel consisted of a series of oxidation and combustion reactions, accompanied by significantly exothermal effects. Highly reactive nanosized ZnTiO3powders were successfully obtained at 850 °C with particle size ~50 nm. By comparison, the aqueous sol-gel process was the most effective and least expensive technique used for the preparation of ZnTiO3nanopowders.

THE INVESTIGATION ON STABILITY AND STRUCTURAL PROPERTIES OF COHESION-BASED NANOSTRUCTURES MATERIAL

2013 ◽  
Vol 27 (27) ◽  
pp. 1350153 ◽  
Author(s):  
ALI BAHARI ◽  
REZA GHOLIPUR ◽  
MARYAM DERAKHSHI
Keyword(s):  
Annealing Temperature ◽  
Sol Gel ◽  
Growth Mode ◽  
X Ray Diffraction ◽  
Low Temperature Synthesis ◽  
Temperature Synthesis ◽  
X Ray ◽  
Annealing Temperatures ◽  
Atomic Force ◽  
Transmission Electron

Styrene-doped ZrLaO y nanostructures were obtained by sol–gel method low-temperature synthesis. The nanostructures were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscope (AFM) and transmission electron microscopy (TEM) techniques. The observation using SEM and TEM revealed that the ring-shaped nanostructures were very uniform. Further characterization using XRD disclosed that the cohesion of the samples was controllable with annealing temperatures in the range of 800–1500°C. Cohesion property was investigated for the samples. The cohesion increased when increasing the annealing temperature. This was linked to the reinforcement of the oxygen bound on the ZrLaO y nanostructures The shape of nanostructures showed a transformation from a ring-shaped growth mode to a hole-surfaced growth mode with increasing annealing temperature. The styrene-doped ZrLaO y nanostructures with controllable crystallinity will have great potential for various applications in fuel, cells, batteries, electronics devices and chemical sensors.

Pd–P Hydrogenation Catalyst: Nanoparticle Nature and Surface Layer State

NANO ◽  
2016 ◽  
Vol 11 (06) ◽  
pp. 1650065 ◽  
Author(s):  
Lyudmila B. Belykh ◽  
Nikita I. Skripov ◽  
Tatyana P. Sterenchuk ◽  
Vitaliy A. Umanets ◽  
Fedor K. Schmidt
Keyword(s):  
High Selectivity ◽  
White Phosphorus ◽  
Low Temperature Synthesis ◽  
Temperature Synthesis ◽  
Palladium Clusters ◽  
X Ray ◽  
Liquid Phase Hydrogenation ◽  
Nanoparticle Surface ◽  
Transmission Electron ◽  
Catalyst Nanoparticle

The Pd–P selective catalyst for liquid-phase hydrogenation of o-chloronitrobenzene (o-CNB) was obtained by the reduction of Pd(acac)2 with hydrogen at 80∘C in the presence of white phosphorus (P/Pd = 1) in N,N-dimethylformamide (DMF). It has been shown [(high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDX), X-ray powder diffraction (XRD)] that such low-temperature synthesis of the Pd–P catalyst affords nanoparticles of palladium phosphides (Pd5P2, PdP2), the Pd5P2 phosphide being prevailing. On the nanoparticle surface, palladium is present as a phosphide (BE (Pd3d5∕2) = 336.2 eV; BE (P2p3∕2) = 130 eV) and as palladium clusters of ≈ 1 nm in diameter. The formation of the Pd–P catalyst proceeds through a number of stages: a redox process between Pd(acac)2 and white phosphorus affording mainly PdP2 nanoparticles, H3PO3 and acacH; next follows the reduction of unreacted Pd(acac)2 with hydrogen at 80∘C and the reaction of Pd(0) atoms with each other and with PdP2. It is assumed that formation of small palladium clusters on the surface of the Pd5P2 nanoparticles ensures the high selectivity of the Pd–P catalyst in the o-CNB hydrogenation.

Low Temperature Synthesis of CdSe Quantum Dots with Amine Derivative and Their Chemical Kinetics

2010 ◽  
Vol 49 (5) ◽  
pp. 05EA03 ◽  
Author(s):  
Seongmi Hwang ◽  
Youngmin Choi ◽  
Sunho Jeong ◽  
Hakyun Jung ◽  
Chang Gyoun Kim ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Low Temperature ◽  
Chemical Kinetics ◽  
Cdse Quantum Dots ◽  
Low Temperature Synthesis ◽  
Temperature Synthesis ◽  
Amine Derivative

scholarly journals Low temperature synthesis of bioactive materials

Cerâmica ◽  
2011 ◽  
Vol 57 (342) ◽  
pp. 166-172 ◽  
Author(s):  
L. C. Bandeira ◽  
P. S. Calefi ◽  
K. J. Ciuffi ◽  
E. J. Nassar ◽  
I. M. M. Salvado ◽  
...  
Keyword(s):  
Sol Gel ◽  
High Symmetry ◽  
Low Temperature Synthesis ◽  
Temperature Synthesis ◽  
Bioactive Materials ◽  
Transmission Electron ◽  
Structural Probe ◽  
Two Phases ◽  
The Eu

Bioactive materials possess properties that allow them to interact with natural tissues to induce reactions that favor the development and regeneration of those tissues. In this study, silica was prepared by the sol-gel method, using tetraethylorthosilicate as the precursor. The calcium and phosphor sources used here were calcium ethoxy and phosphoric acid, respectively, in ethanol solvent. The solid obtained was dried at 50 ºC. In vitro bioactivity assays were performed by soaking the materials in simulated body fluid (SBF). The samples were characterized by transmission electron microscopy (TEM), thermal analysis and photoluminescence. TEM images of the samples before contact with SBF revealed amorphous aggregates and after 12 days in SBF showed two phases, one amorphous with large quantities of Si and O, and the other a crystalline phase whose composition contained Ca and P. The electron diffraction pattern showed a planar distance of 2.86 Å, corresponding to 2θ = 32.2º. This was ascribed to hydroxyapatite. The Eu III was used as structural probe. The relative band intensity correspondent the transition 5D0 → 7F2 / 5D0 → 7F1 showed a high symmetry surrounding the Eu III ion. These materials, produced by the sol-gel route, open up new possibilities for obtaining bioactive biomaterials for medical applications.

Low Temperature Synthesis of Onion-Like Fullerenes Using Aluminum Hydroxide Supported Iron Catalyst

2012 ◽  
Vol 490-495 ◽  
pp. 3315-3318 ◽  
Author(s):  
Lei Shan Chen ◽  
Cun Jing Wang
Keyword(s):  
Low Temperature ◽  
Aluminum Hydroxide ◽  
Vapor Deposition ◽  
Iron Catalyst ◽  
Chemical Vapor ◽  
Tubular Furnace ◽  
Low Temperature Synthesis ◽  
Temperature Synthesis ◽  
Transmission Electron ◽  
Effects Of Temperature

Synthesis of onion-like fullerenes was carried out by chemical vapor deposition in a tubular furnace using iron catalyst supported on aluminum hydroxide at 400°C, 460°C, 600°C, 700°C, 800°C, 900°C and 1000°C, respectively, in the presence of argon as carrier gas and acetylene as the carbon source. The samples synthesized were characterized by high-resolution transmission electron microscopy, and the effects of temperature on the morphologies of the samples were investigated. The results show that the onion-like fullerenes prepared at the low temperature 400°C had the highest purity and good quality.

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.

Low-Temperature Synthesis of Complex Perovskite Ba(Zn1/3Nb2/3)O3 Nano-Powders by Aqueous Sol-Gel Process

2014 ◽  
Vol 543-547 ◽  
pp. 3737-3740
Author(s):  
Quan Jing Mei ◽  
Cong Ying Li ◽  
Jing Dong Guo ◽  
Gui Wang ◽  
Hai Tao Wu
Keyword(s):  
Sol Gel ◽  
Zinc Nitrate ◽  
X Ray Diffraction ◽  
Complex Perovskite ◽  
Low Temperature Synthesis ◽  
Temperature Synthesis ◽  
Calcination Process ◽  
X Ray ◽  
Transmission Electron ◽  
Sol Gel Process

The complex perovskite Ba (Zn1/3Nb2/3)O3was successfully synthesized by the aqueous sol-gel method using niobium pentoxide, nitrate barium and zinc nitrate as starting materials instead of expensive organic solvent and metal alkoxides. The as-prepared nanopowders were characterized by X-ray diffraction (XRD), differential thermal analysis (DTA) and transmission electron microscopy (TEM), respectively. The results showed that the calcination process of gel consisted of a series of oxidation and combustion reactions, accompanied by significantly exothermal effects. Highly reactive nanosized Ba (Zn1/3Nb2/3)O3powders were successfully obtained at 850 °C with particle size ~100 nm. By comparison, the aqueous sol-gel process was the most effective and least expensive technique used for the preparation of Ba (Zn1/3Nb2/3)O3nanopowders.

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