scholarly journals Size-Selective Precipitation and Aggregate Reduction of FePt-Based Nanoparticles

2018 ◽  
Vol 2018 ◽  
pp. 1-5 ◽  
Author(s):  
Pharunee Sarmphim ◽  
Pongsakorn Jantaratana ◽  
Chitnarong Sirisathitkul
Keyword(s):  
Electron Microscopy ◽  
Size Distribution ◽  
Data Storage ◽  
Ultrasonic Power ◽  
Narrow Size Distribution ◽  
Selective Precipitation ◽  
Density Data ◽  
Iron Platinum ◽  
Transmission Electron ◽  
By Products

Magnetic nanoparticles with a narrow size distribution are desirable for applications in ultra-high density data storage and biomedicine. In this work, the size-selective precipitation and aggregate reduction were combined to classify superparamagnetic iron platinum- (FePt-) based nanoparticles. The size-selective precipitation was implemented with the variation in the amount of ethanol. In the first condition, the ratio of ethanol-to-nanosuspension of 3 : 4 was used in the precipitation twice. By contrast, the second condition employed the ratios of ethanol-to-nanosuspension of 4 : 4 in the first precipitation and 5 : 4 in the second precipitation. The first precipitation successfully sorted out the aggregated particles, and the second precipitation collected particles with a narrow size distribution. The increase in ethanol enhanced the monodispersity of nanoparticles as shown by transmission electron microscopy (TEM) images and size distribution curves. In addition, large aggregated by-products from the precipitation stage were sonicated with the addition of surfactants. The increase in ultrasonic power reduces the aggregation, but the longer sonication led to an uneven distribution.

An Experimental Study on Synthesis and Characterization of Silica Nanoparticles Prepared by Sol-Gel Method

2007 ◽  
Vol 553 ◽  
pp. 245-251
Author(s):  
Ali Shokuhfar ◽  
Tolou Shokuhfar ◽  
M. Ghazinejad ◽  
R. Babazade ◽  
S. Tabatabae
Keyword(s):  
Electron Microscopy ◽  
Silica Nanoparticles ◽  
Size Distribution ◽  
Sol Gel ◽  
Sio2 Nanoparticles ◽  
Industrial Applications ◽  
Silica Particles ◽  
Narrow Size Distribution ◽  
Molar Ratios ◽  
Transmission Electron

Monodispersed nanometer-sized particles proved to be very important and advantageous in many industrial applications. One of the notable groups of these particles is silica (SiO2) nanoparticles which are widely utilized in developing numerous products such as electrical and thermal insulators, humidity sensors, varnish, etc. Since the quality of some of these products depends highly on the purity and size distribution of the silica particles, it is necessary to produce silica nanoparticles of narrow size distribution and very high purity. In this research silica nanoparticles, with a relatively narrow size distribution, have been synthesized via the hydrolysis reaction of tetraethoxisilane (TEOS) in the solution of deionized water and ethanol (C2H5OH), and in the presence of ammonia (NH3) as a catalyst. The nature, morphology and the size of the silica particles has been studied using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and X-ray diffraction. Results indicate that the morphology, structure and the diameter of silica particles depend strongly on the molar ratios of the reactants.

Preparation and Characterization of Electrosprayed Nanoparticles containing Ethyl Maltol Flavor

2021 ◽  
Vol 1042 ◽  
pp. 131-136
Author(s):  
Megdi Eltayeb
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Stearic Acid ◽  
Size Distribution ◽  
Entrapment Efficiency ◽  
Narrow Size Distribution ◽  
Transmission Electron

In this study, electrospraying is used to prepare electrosprayed multicomponent nanoparticles of ethylcellulose and stearic acid entrapping ethyl maltol. Electrospraying nanoparticles produced were ≤100 nm diameter and narrow size distribution (polydispersity index 0.26) is achieved. The ethyl maltol entrapment efficiency and yield were approximately 88% and 76%, respectively. The presence of ethyl maltol flavor within the polymeric electrosprayed nanoparticles was shown by Fourier transform infrared spectroscopy. The morphology of the electrosprayed multicomponent nanoparticles generated was studied by transmission electron microscopy.

Amphiphilic architectures based on fullerene and calixarene platforms: From buckysomes to shape-persistent micelles

2008 ◽  
Vol 80 (3) ◽  
pp. 571-587 ◽  
Author(s):  
Andreas Hirsch
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Transfer ◽  
Size Distribution ◽  
Photoinduced Electron Transfer ◽  
Building Blocks ◽  
Water Soluble ◽  
Narrow Size Distribution ◽  
Transmission Electron ◽  
Supramolecular Aggregation

The supramolecular aggregation properties of new prototypes of artificial amphiphiles consisting of fullerene or calixarene building blocks serving as platforms for the connection of hydrophobic and dendritic hydrophilic groups are reported. Very water-soluble monoadducts of C60 carrying a defined number of negative charges at a given pH were hybridized with cationic porphyrins including cyctochrome C and investigated with respect to photoinduced electron transfer. Fullerene adducts with dendritic deprotected sugar addends self-assemble to supramolecular sugar balls in water with a narrow size distribution of the micelles of around 4 nm. Various examples of cone- or T-shaped amphiphiles involving calixarene and fullerene cores self-organize to the first examples of shape-persistent micelles whose supramolecular arrangement in water has been determined with unprecedented precision based on the analysis of cryo-transmission electron microscopy (TEM) investigations.

scholarly journals The Domain and Microstructure of Resin-Bonded Magnets

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2849
Author(s):  
Marcin Jan Dośpiał
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Size ◽  
Size Distribution ◽  
Domain Structure ◽  
Grain Size Distribution ◽  
Exchange Interactions ◽  
Force Microscopy ◽  
Transmission Electron ◽  
Scanning Electron

This paper presents domain and structure studies of bonded magnets made from nanocrystalline Nd-(Fe, Co)-B powder. The structure studies were investigated using scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Mössbauer spectroscopy and X-ray diffractometry. On the basis of performed qualitative and quantitative phase composition studies, it was found that investigated alloy was mainly composed of Nd2(Fe-Co)14B hard magnetic phase (98 vol%) and a small amount of Nd1.1Fe4B4 paramagnetic phase (2 vol%). The best fit of grain size distribution was achieved for the lognormal function. The mean grain size determined from transmission electron microscopy (TEM) images on the basis of grain size distribution and diffraction pattern using the Bragg equation was about ≈130 nm. HRTEM images showed that over-stoichiometric Nd was mainly distributed on the grain boundaries as a thin amorphous border of 2 nm in width. The domain structure was investigated using a scanning electron microscope and metallographic light microscope, respectively, by Bitter and Kerr methods, and by magnetic force microscopy. Domain structure studies revealed that the observed domain structure had a labyrinth shape, which is typically observed in magnets, where strong exchange interactions between grains are present. The analysis of the domain structure in different states of magnetization revealed the dynamics of the reversal magnetization process.

scholarly journals Rapid Synthesis of Gold Nano-Particles Using Pulse Waved Potential in a Non-Aqueous Electrolyte

2017 ◽  
Vol 62 (2) ◽  
pp. 1389-1392
Author(s):  
J.G. Jang ◽  
J.-O. Lee ◽  
C.K. Lee
Keyword(s):  
Electron Microscopy ◽  
Size Distribution ◽  
Aqueous Electrolyte ◽  
Supporting Electrolyte ◽  
Nano Particles ◽  
Rapid Synthesis ◽  
Imidazolium Chloride ◽  
Transmission Electron ◽  
Potentiostatic Electrodeposition ◽  
Pulsed Electrodeposition

AbstractRapid synthesis of gold nanoparticles (AuNPs) by pulsed electrodeposition was investigated in the non-aqueous electrolyte, 1-ethyl-3-methyl-imidazoliumbis(trifluoro-methanesulfonyl)imide ([EMIM]TFSI) with gold trichloride (AuCl3). To aid the dissolution of AuCl3, 1-ethyl-3-methyl-imidazolium chloride ([EMIM]Cl) was used as a supporting electrolyte in [EMIM]TFSI. Cyclic voltammetry experiments revealed a cathodic reaction corresponding to the reduction of gold at −0.4 V vs. Pt-QRE. To confirm the electrodeposition process, potentiostatic electrodeposition of gold in the non-aqueous electrolyte was conducted at −0.4 V for 1 h at room temperature. To synthesize AuNPs, pulsed electrodeposition was conducted with controlled duty factor, pulse duration, and overpotential. The composition, particle-size distribution, and morphology of the AuNPs were confirmed by field-emission scanning electron microscopy (FE-SEM), energy-dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). The electrodeposited AuNPs were uniformly distributed on the platinum electrode surface without any impurities arising from the non-aqueous electrolyte. The size distribution of AuNPs could be also controlled by the electrodeposition conditions.

Synthesis Route towards Fine and Monodisperse Ni Nanoparticles via Hot-Injection Approach

2013 ◽  
Vol 393 ◽  
pp. 146-151 ◽  
Author(s):  
N.R. Nik Roselina ◽  
Aziz Azizan ◽  
Koay Mei Hyie ◽  
C.M. Mardziah ◽  
Salmiah Kasolang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Size Distribution ◽  
Reaction Rate ◽  
Fine Particles ◽  
Synthesis Temperature ◽  
Ni Nanoparticles ◽  
One Pot ◽  
Transmission Electron ◽  
Hot Injection

Manipulation of adding sequences have been found to influence the reaction rate, thus made it easier to produced controllable Ni nanoparticles. Hot-injection approach shown capability to significantly reduce the production time of Ni nanoparticles compared to the conventional one-pot synthesis. With minor modification on conventional polyol method, narrow, monodispersed and highly yield spherical nickel (Ni) nanoparticles were successfully produced at synthesis temperature of 60°C. Three mixing methods were investigated to study its efficiency towards producing rapid and narrower size distribution of Ni nanoparticles. Reduction processes were proposed each of the method. As-synthesized Ni nanoparticles were characterized with Transmission Electron Microscopy (TEM), Scanning Transmission Electron Microscopy (STEM) and Fourier transform infrared spectroscopy (FTIR) to analyze the size, morphology and interaction of reactants. Fine particles size distribution revealed that when hydrazine was first heated, reaction rate improved tremendously.

A Technique for the Preparation of Thin-Film Cross-Sections for Transmission Electron Microscopy

1990 ◽  
Vol 199 ◽  
Author(s):  
M. Libera ◽  
T. A. Nguyen ◽  
C. Hwang
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Thin Films ◽  
Data Storage ◽  
Cross Sections ◽  
Film Plane ◽  
Microstructural Study ◽  
Transmission Electron ◽  
Sophisticated Equipment ◽  
Tem Grid

ABSTRACTA number of techniques for producing TEM cross-sections of thin films have been described in recent years as the need for improved and more-thorough microstructural study of thin-film materials has grown. We have developed a method for producing such cross-sections which involves little sophisticated equipment other than an ion mill for thinning. Following the method of Bravman and Sinclair (J. Elec. Micrs. Tech 1,53–61 (1984)), the film of interest is either deposited on or epoxied to a silicon wafer and a composite of six silicon beams (=3mm × 25mm × 0.5mm) is fabricated. Slices are cut from this composite perpendicular to the film plane, and each slice is mechanically thinned by a series of simple grinding and polishing steps to ∼ 50–100μm. Dimpling is not necessary. The specimen is mounted onto a slotted TEM grid which provides a vehicle for safe handling, and the specimen is ion milled to perforation. We have found the technique to be relatively fast, reliable, and simple. Its success hinges on minimizing the amount of direct handling required when the specimen is thin and fragile. We present a detailed recipe describing its various steps and show typical results from studies of thin films for data-storage applications.

scholarly journals Synthesis of CdSe/ZnS and CdTe/ZnS Quantum Dots: Refined Digestive Ripening

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Sreeram Cingarapu ◽  
Zhiqiang Yang ◽  
Christopher M. Sorensen ◽  
Kenneth J. Klabunde
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Quantum Dots ◽  
Scale Up ◽  
Trioctylphosphine Oxide ◽  
Cdse Qds ◽  
Selective Precipitation ◽  
Digestive Ripening ◽  
Cdte Qds ◽  
Transmission Electron

We report synthesis of CdSe and CdTe quantum dots (QDs) from the bulk CdSe and CdTe material by evaporation/co-condensation using the solvated metal atom dispersion (SMAD) technique and refined digestive ripening. The outcomes of this new process are (1) the reduction of digestive ripening time by employing ligands (trioctylphosphine oxide (TOPO) and oleylamine (OA)) as capping agent as well as digestive ripening solvent, (2) ability to tune the photoluminescence (PL) from 410 nm to 670 nm, (3) demonstrate the ability of SMAD synthesis technique for other semiconductors (CdTe), (4) direct comparison of CdSe QDs growth with CdTe QDs growth based on digestive ripening times, and (5) enhanced PL quantum yield (QY) of CdSe QDs and CdTe QDs upon covering with a ZnS shell. Further, the merit of this synthesis is the use of bulk CdSe and CdTe as the starting materials, which avoids usage of toxic organometallic compounds, eliminates the hot injection procedure, and size selective precipitation processes. It also allows the possibility of scale up. These QDs were characterized by UV-vis, photoluminescence (PL), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and powder XRD.

Sign in / Sign up

Export Citation Format

Share Document