Synthesis of water dispersed Fe3O4@ZnO Composite Nanoparticles by the Polyol Method

2012 ◽  
Vol 1449 ◽  
Author(s):  
Yesusa Collantes ◽  
Oscar Perales-Perez ◽  
Oswald N. C. Uwakweh ◽  
J.-F.Guinel Maxime
Keyword(s):  
Room Temperature ◽  
Water Soluble ◽  
Composite Nanoparticles ◽  
Molar Ratio ◽  
Zno Nps ◽  
Transmission Electron ◽  
Maximum Magnetization ◽  
Crystallite Sizes ◽  
Excitonic Emission ◽  
Magnetite Nanocrystals

ABSTRACTWater-soluble Fe3O4@ZnO composite nanoparticles (NPs) were synthesized using a polyol route. The effects of the addition of the ZnO phase were evaluated by varying the Zn/Fe molar ratio in the 0.25-1.00 range as a function of the reaction time. X-ray diffractometry confirmed the formation of the magnetite and ZnO phases and suggested the possible formation of a composite structure. Also, using this method, pure magnetite and ZnO NPs were synthesized. The average crystallite sizes were estimated to 6.3 ± 0.3 nm and 8.6 ± 0.6 nm for magnetite and ZnO NPs, respectively. The samples were examined using transmission electron microscopy. Fourier transform infrared spectra indicated the presence of adsorbed species onto the solids surface, which may explain the good stability of the materials in water. Photoluminescence measurements at room temperature for pure ZnO nanoparticles exhibited the characteristic excitonic emission around 395 nm. Vibrating Sample Magnetometer measurements at room temperature evidenced the superparamagnetic behavior of magnetite nanocrystals, with a saturation magnetization of 60emu/g. The maximum magnetization ranged from 28 to 54emu/g for the composite NPs. Mössbauer spectroscopy measurements at room temperature showed evidence of evolving Fe-sites associated to superparamagnetic particles, as reflected on the coexistence of prominent doublet peaks and very weak sextet peaks.

A Facile, “Green” One – Step, Room Temperature Synthesis of a Series of monodispersed MSe(M = Cd or Zn) Water Dispersible Nanoparticles

2008 ◽  
Vol 1138 ◽  
Author(s):  
Oluwatobi S. Oluwafemi ◽  
Neerish Revaprasadu
Keyword(s):  
Room Temperature ◽  
Metal Salt ◽  
Water Soluble ◽  
Synthetic Approach ◽  
Temperature Synthesis ◽  
Water Dispersible ◽  
Aspect Ratios ◽  
Transmission Electron ◽  
One Step ◽  
Capping Ligands

AbstractWe herein report a facile, ‘green’ one- step synthesis of a series of monodispersed water-soluble selenide nanoparticles at room temperature. The capping ligands used include, cysteine, methionine, ascorbic acid and starch which function as agents of solubilisation, stabilization and conjugation sites for biomolecules. The synthetic approach involves the addition of an appropriate volume of selenide ion produced via the reduction of selenium powder in water to an aqueous solution containing the ligand- metal salt (MCl2 M = Zn or Cd). Optical spectroscopy shows that the particles are of high quality while the transmission electron microscopy (TEM) of the samples shows variation in shapes ranging from dots to rods of high and low aspect ratios.

One-Step Synthesis of CdSe Quantum Dots by Using Hydrazine Hydrate Reduction of Selenium Dioxide

2018 ◽  
Vol 71 (7) ◽  
pp. 524 ◽  
Author(s):  
Rongfang Wang ◽  
Xingming Wei ◽  
Jun Xie ◽  
Bomei Wang ◽  
Xiaotong He
Keyword(s):  
Quantum Dots ◽  
Hydrazine Hydrate ◽  
Selenium Dioxide ◽  
Water Soluble ◽  
Molar Ratio ◽  
Cdse Quantum Dots ◽  
Cdse Qds ◽  
Original Solution ◽  
Transmission Electron ◽  
Average Size

Hydrazine hydrate was used as a novel reducing agent for the synthesis of water soluble and stable cadmium selenide (CdSe) quantum dots (QDs). The as-prepared CdSe quantum dots were investigated by X-ray powder diffraction, high-resolution transmission electron microscopy, photoluminescence, and UV-vis absorption spectroscopy analyses. The results show that the as-prepared CdSe QDs possess a cubic crystal structure and an average size of 2 nm. The effects of the pH of the original solution, thioglycollic acid (TGA)/Cd2+ molar ratio (nTGA/nCd2+), and the Cd/Se molar ratio on the luminescence properties of CdSe QDs were also systematically analysed.

Synthesis and Optical Properties of L-Cysteine Hydrochloride-Stabilized CdSe Nanocrystals in a New Alkali System

2008 ◽  
Vol 8 (3) ◽  
pp. 1178-1182 ◽  
Author(s):  
Bin Feng ◽  
Feng Teng ◽  
Ai-Wei Tang ◽  
Yan Wang ◽  
Yan-Bing Hou ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Optical Properties ◽  
Photoelectron Spectroscopy ◽  
Water Soluble ◽  
Molar Ratio ◽  
Cdse Nanocrystals ◽  
X Ray ◽  
Transmission Electron ◽  
Cysteine Hydrochloride

Water-soluble CdSe nanocrystals were synthesized in a new alkali system at lower temperatures by using L-cysteine hydrochloride as a stabilizer and Na2SeSO3 as a selenium source to enable the synthesis of CdSe nanocrystals in a wider range of pHvalues. The CdSe nanocrystal powder was characterized by X-ray powder diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy. We systematically investigated the effect of synthesis conditions on the optical properties of the L-cysteine hydrochloride-stabilized CdSe nanocrystals, and found that different sizes of CdSe nanocrystals can be obtained by changing the pHvalue, the molar ratio of L-cysteine hydrochloride to Cd2+, or the refluxing time. The emission maxima of the obtained CdSe nanocrystals can be tuned in a wider range from 477 to 575 nm by changing the pHvalue from 7 to 13. We observed an obvious blue-shift of the absorption and photoluminescence peak position by varying the molar ratio of L-Cys to Cd2+ from 3.5:1 to 2:1 at the same pHvalue. The size of the obtained nanocrystals increased and the full width at half maximum became narrower as reflux time increased. Transmission electron microscopy images indicate that the as-prepared CdSe nanocrystals have a good dispersion, which means that L-cysteine hydrochloride can control the grouping of CdSe nanocrystals excellently as a stabilizer in the new alkali system.

Effect of Gallium Loading on Reducibility and Dispersion of Copper-Based Catalyst

2015 ◽  
Vol 659 ◽  
pp. 211-215
Author(s):  
Parncheewa Udomsap ◽  
Somsak Supasitmongkol
Keyword(s):  
Copper Oxide ◽  
Precipitation Method ◽  
Molar Ratio ◽  
Reduction Peak ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Crystallite Sizes ◽  
Copper Phase ◽  
Temperature Programmed ◽  
Co Precipitation

The effect of gallium-promoted copper-based catalysts has been investigated in connection with the characteristic of the active copper phase. CuO-ZnO-Ga2O3catalysts with different gallium loadings were prepared using oxalate co-precipitation method. The effects of gallium loading on the properties of catalysts were studied by means of X-ray diffraction (XRD), transmission electron microscopy (TEM) and temperature-programmed reduction (TPR). The dispersion and metal area of copper were also determined by dissociative nitrous (N2O) adsorption technique conducted on a metal dispersion analyzer (BELCAT). The TPR profiles showed that the presence of two different reduction regions in the CuO-ZnO catalysts can be attributed to the reduction of highly dispersed copper oxide species (reduced at 246 °C) and bulk-like CuO (reduced at above 390 °C). By contrast, the only low-temperature reduction peak was presented in the TPR profiles after the Ga2O3loading was higher than 4 wt%. With the same molar ratio (Cu/Zn = 2:1), the reducibility of CuO-ZnO-Ga2O3was found to be more facile than CuO-ZnO due to the lower copper oxide crystallite sizes of gallium-promoted catalysts. Higher Ga2O3loadings resulted in an increase in both copper dispersion and metal surface area of all the catalysts studied in good agreement with the reduction behaviors in the TPR profiles, although all the gallium-promoted catalysts were slightly different for the reducibility.

scholarly journals Room Temperature Synthesis of Nanostructured ZnO: Active Visible Photocatalyst in the Degradation of Methylene Blue

2021 ◽  
pp. 13-20
Author(s):  
Amine El Farrouji ◽  
Rachid Mohamed Tchalala ◽  
Abderrahim Chihab Eddine ◽  
Ahmad Mehdi ◽  
Larbi El Firdoussi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Methylene Blue ◽  
Room Temperature ◽  
Phase Method ◽  
Zno Nps ◽  
Experimental Conditions ◽  
X Ray ◽  
Transmission Electron ◽  
Solution Phase Method ◽  
Kinetics Of

Nanostructured ZnO was prepared using a facile solution-phase method at room temperature without need to calcination. Oxidation of zinc sulfate by sodium hypochlorite in the presence of polyethylene glycol (PEG) and sodium hydroxide (NaOH) gave pure nanostructured zinc oxide (ZnO-NPs). The structure and physicochemical properties of the material were determined by X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (IR), Energy Dispersive X-ray Spectroscopy (EDS), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), UV–Vis diffuse reflectance and their optical Properties. ZnO particles were successfully distributed in two-dimensional sheet with a nanometric thickness and a random distribution. The activity was evaluated for photocatalytic degradation of methylene blue (MB) by a study of experimental conditions such as the effect of the mass of the catalyst, the effect of the initial concentration of the dye and the effect of the volume of the oxidizing agent. The kinetics of the reaction follow a pseudo-first order.

scholarly journals Deep Eutectic Solvents as an Alternate to Other Harmful Solvents

2021 ◽  
Vol 12 (1) ◽  
pp. 847-860
Keyword(s):  
Room Temperature ◽  
Deep Eutectic Solvents ◽  
Water Soluble ◽  
Molar Ratio ◽  
Drug Solubility ◽  
Green Solvents ◽  
Liquid Form ◽  
Poorly Water Soluble ◽  
Carbon Dioxide Co2 ◽  
Solventless Reaction

Solvents generally in liquid form, are used to dissolve, dilute, suspend any substances or extract other materials. More than one-third of the drugs listed in the various Pharmacopeias fall into the poorly water-soluble or water-insoluble categories. For more than 200 years, traditional solvents could be used as a solvent for substances that were insoluble in water. But the usage of these types of solvents should be decreased because these types of solvents are volatile, flammable, and often toxic. Also, the industrialist’s usages in different types of processes prove the risk for workers. In recent years, several solvents have been proposed to be the greener replacement for traditional solvents. Replacing hazardous chemicals with more environmentally friendly alternatives is a matter of current interest, in line with the philosophy of Green Chemistry. The use of nontraditional or nonconventional solvents such as supercritical fluids (SCFs) such as Carbon dioxide (CO2) and water, fluorous solvents, solventless reaction Ionic liquids (ILs) and their derivatives [polymeric ILs and magnetic ILs], and deep eutectic solvents (DESs) are alternatives for environmentally unfriendly traditional solvents. Among them, DES is a neoteric class of green solvents defined as a mixture of two or more compounds that are typically solid at room temperature, but when combined at a particular molar ratio, changes into a liquid at room temperature. It is assumed that eutectic mixtures show low volatility, have a broad liquid range, and are water-compatible, non-flammable, non-toxic, biocompatible, and eco-friendly. Eutectic solvents have been useful in several pharmaceutical fields, such as the increase of drug solubility, permeation, and absorption.

Domain Formation in Synthetic Quartz

1971 ◽  
Vol 29 ◽  
pp. 156-157
Author(s):  
Joseph J. Comer
Keyword(s):  
Electron Beam ◽  
Room Temperature ◽  
Domain Formation ◽  
Synthetic Quartz ◽  
Transmission Electron ◽  
Black Spots ◽  
Diffraction Mode ◽  
Domain Boundaries ◽  
Kikuchi Lines ◽  
Straight Lines

Domains visible by transmission electron microscopy, believed to be Dauphiné inversion twins, were found in some specimens of synthetic quartz heated to 680°C and cooled to room temperature. With the electron beam close to parallel to the [0001] direction the domain boundaries appeared as straight lines normal to <100> and <410> or <510> directions. In the selected area diffraction mode, a shift of the Kikuchi lines was observed when the electron beam was made to traverse the specimen across a boundary. This shift indicates a change in orientation which accounts for the visibility of the domain by diffraction contrast when the specimen is tilted. Upon exposure to a 100 KV electron beam with a flux of 5x 1018 electrons/cm2sec the boundaries are rapidly decorated by radiation damage centers appearing as black spots. Similar crystallographio boundaries were sometimes found in unannealed (0001) quartz damaged by electrons.

Scanning and Transmission Electron Microscopy of Human Red Blood Cells

1969 ◽  
Vol 27 ◽  
pp. 44-45
Author(s):  
A.J. Tousimis ◽  
T.R. Padden
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Blood Cells ◽  
Room Temperature ◽  
Type Specimen ◽  
New Combination ◽  
Human Red Blood Cells ◽  
Transmission Electron ◽  
Microscope Slides ◽  
Scanning Electron

The size, shape and surface morphology of human erythrocytes (RBC) were examined by scanning electron microscopy (SEM), of the fixed material directly and by transmission electron microscopy (TEM) of surface replicas to compare the relative merits of these two observational procedures for this type specimen.A sample of human blood was fixed in glutaraldehyde and washed in distilled water by centrifugation. The washed RBC's were spread on freshly cleaved mica and on aluminum coated microscope slides and then air dried at room temperature. The SEM specimens were rotary coated with 150Å of 60:40- gold:palladium alloy in a vacuum evaporator using a new combination spinning and tilting device. The TEM specimens were preshadowed with platinum and then rotary coated with carbon in the same device. After stripping the RBC-Pt-C composite film, the RBC's were dissolved in 2.5N HNO3 followed by 0.2N NaOH leaving the preshadowed surface replicas showing positive topography.

Formation of Dislocation Channels in Neutron Irradiated Molybdenum

1972 ◽  
Vol 30 ◽  
pp. 672-673
Author(s):  
S. Mahajan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ambient Temperature ◽  
Room Temperature ◽  
Channel Formation ◽  
Early Stages ◽  
Transmission Electron ◽  
Three Stages ◽  
Two Stages ◽  
Polycrystalline Molybdenum

The evolution of dislocation channels in irradiated metals during deformation can be envisaged to occur in three stages: (i) formation of embryonic cluster free regions, (ii) growth of these regions into microscopically observable channels and (iii) termination of their growth due to the accumulation of dislocation damage. The first two stages are particularly intriguing, and we have attempted to follow the early stages of channel formation in polycrystalline molybdenum, irradiated to 5×1019 n. cm−2 (E > 1 Mev) at the reactor ambient temperature (∼ 60°C), using transmission electron microscopy. The irradiated samples were strained, at room temperature, up to the macroscopic yield point.Figure 1 illustrates the early stages of channel formation. The observations suggest that the cluster free regions, such as A, B and C, form in isolated packets, which could subsequently link-up to evolve a channel.

(111) Monocrystalline Nickel Films

1972 ◽  
Vol 30 ◽  
pp. 512-513
Author(s):  
T.E. Pratt ◽  
R.W. Vook
Keyword(s):  
Film Thickness ◽  
Deposition Rate ◽  
Room Temperature ◽  
Narrow Range ◽  
High Vacuum ◽  
Residual Pressure ◽  
Temperature Dependent ◽  
Deposition Parameters ◽  
Transmission Electron ◽  
Substrate Temperatures

(111) oriented thin monocrystalline Ni films have been prepared by vacuum evaporation and examined by transmission electron microscopy and electron diffraction. In high vacuum, at room temperature, a layer of NaCl was first evaporated onto a freshly air-cleaved muscovite substrate clamped to a copper block with attached heater and thermocouple. Then, at various substrate temperatures, with other parameters held within a narrow range, Ni was evaporated from a tungsten filament. It had been shown previously that similar procedures would yield monocrystalline films of CU, Ag, and Au.For the films examined with respect to temperature dependent effects, typical deposition parameters were: Ni film thickness, 500-800 A; Ni deposition rate, 10 A/sec.; residual pressure, 10-6 torr; NaCl film thickness, 250 A; and NaCl deposition rate, 10 A/sec. Some additional evaporations involved higher deposition rates and lower film thicknesses.Monocrystalline films were obtained with substrate temperatures above 500° C. Below 450° C, the films were polycrystalline with a strong (111) preferred orientation.

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