scholarly journals Effect of Nitric Acid Concentrations on Synthesis and Stability of Maghemite Nanoparticles Suspension

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Irwan Nurdin ◽  
Mohd Rafie Johan ◽  
Iskandar Idris Yaacob ◽  
Bee Chin Ang
Keyword(s):  
Nitric Acid ◽  
Zeta Potential ◽  
Narrow Particle Size Distribution ◽  
Maghemite Nanoparticles ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
The Stability ◽  
Xrd Patterns ◽  
Nanoparticles Suspension

Maghemite(γ-Fe2O3)nanoparticles have been synthesized using a chemical coprecipitation method at different nitric acid concentrations as an oxidizing agent. Characterization of all samples performed by several techniques including X-ray diffraction (XRD), transmission electron microscopy (TEM), alternating gradient magnetometry (AGM), thermogravimetric analysis (TGA), dynamic light scattering (DLS), and zeta potential. The XRD patterns confirmed that the particles were maghemite. The crystallite size of all samples decreases with the increasing concentration of nitric acid. TEM observation showed that the particles have spherical morphology with narrow particle size distribution. The particles showed superparamagnetic behavior with decreased magnetization values at the increasing concentration of nitric acid. TGA measurement showed that the stability temperature decreases with the increasing concentration of nitric acid. DLS measurement showed that the hydrodynamic particle sizes decrease with the increasing concentration of nitric acid. Zeta potential values show a decrease with the increasing concentration of nitric acid. The increasing concentration of nitric acid in synthesis of maghemite nanoparticles produced smaller size particles, lower magnetization, better thermal stability, and more stable maghemite nanoparticles suspension.

Microstructure Characterization of Metal Mixed Oxides

MRS Advances ◽  
2017 ◽  
Vol 2 (64) ◽  
pp. 4025-4030 ◽  
Author(s):  
T. Kryshtab ◽  
H. A. Calderon ◽  
A. Kryvko
Keyword(s):  
Mixed Oxides ◽  
Profile Analysis ◽  
Atomic Resolution ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Reconstruction Procedure ◽  
Transmission Electron ◽  
Xrd Patterns ◽  
Co Precipitation

ABSTRACTThe microstructure of Ni-Mg-Al mixed oxides obtained by thermal decomposition of hydrotalcite-like compounds synthesized by a co-precipitation method has been studied by using X-ray diffraction (XRD) and atomic resolution transmission electron microscopy (TEM). XRD patterns revealed the formation of NixMg1-xO (x=0÷1), α-Al2O3 and traces of MgAl2O4 and NiAl2O4 phases. The peaks profile analysis indicated a small grain size, microdeformations and partial overlapping of peaks due to phases with different, but similar interplanar spacings. The microdeformations point out the presence of dislocations and the peaks shift associated with the presence of excess vacancies. The use of atomic resolution TEM made it possible to identify the phases, directly observe dislocations and demonstrate the vacancies excess. Atomic resolution TEM is achieved by applying an Exit Wave Reconstruction procedure with 40 low dose images taken at different defocus. The current results suggest that vacancies of metals are predominant in MgO (NiO) crystals and that vacancies of Oxygen are predominant in Al2O3 crystals.

Photocatalytic Analysis and Characterization of Zn2SnO4 Nanoparticles Synthesized via Hydrothermal Method with Na2CO3 Mineralizer

2010 ◽  
Vol 97-101 ◽  
pp. 19-22 ◽  
Author(s):  
Yu Shiang Wu ◽  
Wen Ku Chang ◽  
Min Jou
Keyword(s):  
Photocatalytic Activity ◽  
Hydrothermal Process ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Visible Absorption ◽  
Transmission Electron ◽  
Excellent Photocatalytic Activity ◽  
Face Centered ◽  
Xrd Patterns

Zinc stannate Zn2SnO4 (ZTO) nanoparticles were synthesized via a hydrothermal process utilizing sodium carbonate (Na2CO3) as a weak basic mineralizer. The samples were hydrothermally treated at 150, 200, and 250oC for 48 h. The X-ray diffraction (XRD) patterns show that the highly-crystalline ZTO nanostructure could be formed in a well-dispersed manner for the 250°C sample at a particle size of less than 50 nm. As determined from transmission electron microscopy (TEM) results, ZTO nanoparticles are face-centered cubic single crystals agglomerated together. The Raman spectra results showed that the ZTO nanocrystals have a spinel structure. Furthermore, photocatalytic activity was tested with methylene blue (MB) by UV irradiation. The ZTO synthesized by the 2 M Na2CO3 mineralizer at 250oC demonstrated excellent photocatalytic activity. The ZTO treated three different ways had three distinct UV-Visible absorption curves, which directly influences their corresponding photocatalytic activity.

scholarly journals Microstructure Characterization of Welds in X5CrNiCuNb16-4 Steel in Overaged Condition

2019 ◽  
Vol 19 (1) ◽  
pp. 57-69
Author(s):  
A. Ziewiec ◽  
A. Zielińska-Lipiec ◽  
J. Kowalska ◽  
K. Ziewiec
Keyword(s):  
Electron Microscopy ◽  
Aging Time ◽  
Energy Dispersive Spectrometry ◽  
Solution Treatment ◽  
X Ray Diffraction ◽  
Density Distributions ◽  
Transmission Electron ◽  
Steel Welds ◽  
The Stability

AbstractThe paper presents the results of the investigation of microstructure of the welded X5CrNiCuNb16-4 (17-4PH) steel after solution treatment and aging at 620°C for different periods. The microstructure and the phase composition of the steel was investigated using light microscopy (LM), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), transmission electron microscopy (TEM) and the X-ray diffraction (XRD). Hardness was measured for samples aged at different times. Density distributions of Cu precipitates were established. The investigation has shown that the microstructure of the X5CrNiCuNb16-4 steel welds after aging at 620 ° C consists of tempered martensite, fine Cu precipitates and austenite. It was observed that the size of the Cu precipitates increases with increasing the aging time, what affects the decrease of hardness. Simultaneously, the quantity of reversed austenite increases with increase of aging time. It was revealed that enrichment of the austenite in Ni, Cu and C affects the increase of Ms, but this factor does not determine the stability of austenite.

Synthesis and Characterization of a New Amino-Functionalized PMO Material

2013 ◽  
Vol 712-715 ◽  
pp. 271-279
Author(s):  
Fei Ding ◽  
Shuang Xi Liu
Keyword(s):  
Electron Microscopy ◽  
Solid State Nmr ◽  
Alkyl Chain ◽  
Reaction System ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Xrd Patterns

A new organic silicane which is bridged by a long amino-functionalized alkyl chain was prepared and used as the precursor in the synthesis of a series of PMO materials. The organic silicane was added into the reaction system in CH2Cl2and the PMO materials were prepared by a simple stirring method under acidic condition, with a nonionic surfactantBrij 76 as template. To find the proper synthesis condition, the time of stirring and the proportion of organic silicane and TEOS were varied. Liquid and solid state NMR, X-ray diffraction (XRD) patterns, thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and N2-physisorption properties were used to characterize the structures.

scholarly journals Synthesis and Characterization of Birnessite and Cryptomelane Nanostructures in Presence of Hoffmeister Anions

2009 ◽  
Vol 2009 ◽  
pp. 1-8 ◽  
Author(s):  
Marcos A. Cheney ◽  
Robin Jose ◽  
Arghya Banerjee ◽  
Pradip K. Bhowmik ◽  
Shizhi Qian ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Manganese Dioxide ◽  
Chloride Ion ◽  
Reduction Reaction ◽  
X Ray Diffraction ◽  
Hydrothermal Conditions ◽  
Transmission Electron ◽  
Xrd Patterns

The effect of Hoffmeister anions , , and on the structure and morphology of birnessite and cryptomelane-type manganese dioxide nanostructures, produced by the reduction reaction of and in aqueous acidic media, was studied. The syntheses were based on the decomposition of aqueous in presence of HCl for birnessite-type and acidified for cryptomelane-type manganese dioxide under soft hydrothermal conditions. They were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM) techniques. XRD patterns show the formation of birnessite for the first synthesis and a mixture of cryptomelane and birnessite-types for the second synthesis. XRD data revealed that the Hoffmeister anions have a significant effect on the nanostructures of birnessite. The sulphate ion-treated birnessite has the smallest crystals, whereas the chloride ion-treated birnessite has the largest crystals. Their TEM and HRTEM studies revealed a transformation from nanoplatelet morphology for chloride-treated samples to nanofibrous morphology for sulphate-treated birnessite. For the cryptomelane nanostructures, Hoffmeister anions also show a profound effect on their crystalline structures as determined by XRD analyses revealing a transformation of the cryptomelane phase to birnessite phase of . This transformation is also supported by TEM and HRTEM studies.

scholarly journals Effect of Different Mediated Agents on Morphology and Crystallinity of Synthesized Silver Nanowires Prepared by Polyol Process

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Mohammad Taghi Satoungar ◽  
Hamed Azizi ◽  
Saeid Fattahi ◽  
Mohammad Khajeh Mehrizi ◽  
Hedieh Fallahi
Keyword(s):  
Electron Microscopy ◽  
Silver Nanowires ◽  
Vinyl Pyrrolidone ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Solution Field ◽  
Poly Vinyl Pyrrolidone ◽  
Xrd Patterns ◽  
Structural Characterizations

Synthesis and characterization of multiple crystalline silver nanowires (NWs) with uniform diameters were carried out by using 1,2-propandiol and ethylene glycol (EG) as comediated solvents and FeCl3as mediated agent in the presence of poly(vinyl pyrrolidone) (PVP). Experimental data and structural characterizations revealed that AgNWs have evolved from the multiple crystalline seeds initially generated by reduction of AgNO3with EG and 1,2-propandiol followed by reducing Fe(III) to Fe(II) which in turn reacts with and removes adsorbed atomic oxygen from the surfaces of silver seeds. In addition, uniform silver nanowires were obtained by using FeCl2and AlCl3as mediated agents in EG solution. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) showed uniform nanowires in both diameter and length. UV-Vis spectra showed adsorption peaks confirming the formation of nanowires. X-ray diffraction (XRD) patterns displayed the final product with high crystallinity and purity. In this study, a growth mechanism for forming AgNWs was proposed and a comparison between different mediated agents was carried out.

Structural and Magnetic Characterization of LaFe1-xAlxO3 (x = 0 and 0.2) Orthoferrites Synthesized by Gelatin Method

2017 ◽  
Vol 899 ◽  
pp. 227-231 ◽  
Author(s):  
Patrícia Mendonça Pimentel ◽  
J.L.S. Dutra ◽  
A.C. Lima ◽  
J.H. Araújo ◽  
Osmar Bagnato ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Treatment Temperature ◽  
Ferromagnetic Behavior ◽  
X Ray Diffraction ◽  
Magnetic Characterization ◽  
Organic Precursor ◽  
Transmission Electron ◽  
Heat Treated ◽  
Xrd Patterns

The rare-earth orthoferrites (LnFeO3) are promising materials for various applications, such as chemical sensors, cathode for SOFC, catalysts, among others. In general, these oxides are synthesized at temperatures higher than 700 °C. In this work, nanocrystalline LaFe1-xAlxO3 (x=0, x=0.2) powders were synthesized by a method that uses gelatin as organic precursor and heat treated at 400, 600 and 800 °C. The structural and magnetic characterization of powders was carried out by X-ray diffraction (XRD) and vibrating sample magnetometry (VSM). Morphological analysis was performed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The XRD patterns revealed the formation of orthoferrites single phase since 400°C. The powders exhibited weak ferromagnetic behavior at room temperature where the values of saturation magnetization, remanence and coercivity varied with the doping and heat treatment temperature.

Structural and Spectroscopic Characterization of ZrO2:Eu3+ Nanoparticles

2008 ◽  
Vol 8 (12) ◽  
pp. 6431-6436 ◽  
Author(s):  
P. Salas ◽  
N. Nava ◽  
C. Ángeles-Chavez ◽  
E. De la Rosa ◽  
L. A. Díaz-Torres
Keyword(s):  
Raman Spectroscopy ◽  
Crystalline Structure ◽  
Sol Gel ◽  
Tetragonal Zirconia ◽  
Fluorescence Emission ◽  
Spectroscopic Characterization ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Xrd Patterns

ZrO2:Eu3+ nanocrystals were prepared by the sol–gel technique. The structural and luminescence properties of europium doped zirconia with 0.5 to 2 mol% were studied by Mössbauer spectroscopy, Raman spectroscopy, X-ray diffraction (XRD), High Resolution Transmission Electron Microscopy (HRTEM) and photoluminescence (PL) under UV excitation. Structural characterization shows a crystallite size between 16 to 55 nm and monoclinic and tetragonal zirconia phases as the main crystalline structure. XRD patterns shown that the content of the active ions stabilizes the tetragonal structure of ZrO2 at 1000 °C, being 100% for 2 mol% Eu2O3 doped sample. Such results are in agreement with HRTEM and Raman spectroscopy. The Mössbauer spectra of the ZrO2:Eu3+ samples show a single peak near zero velocity which is attributed to Eu+3. Luminescence characterization shows the typical emission band centered at 595 and 611 nm. Change in the structure of such band was observed and explained in terms of crystalline phase change. The dependence between the fluorescence emission and the crystalline structure is discussed.

Growth and Characterization of Well-Aligned RuO2/R-TiO2 Heteronanostructures on Sapphire (100) Substrates by Reactive Magnetron Sputtering

2011 ◽  
Vol 170 ◽  
pp. 78-82
Author(s):  
Hung Pin Hsu ◽  
Ying Sheng Huang ◽  
Chien Nan Yeh ◽  
Yi Min Chen ◽  
Dah Shyang Tsai ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Magnetron Sputtering ◽  
Reactive Magnetron Sputtering ◽  
Reactive Magnetron ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Vertically Aligned ◽  
Xrd Patterns ◽  
Electron Diffractometry

We report the growth of well-aligned RuO2/R-TiO2 heteronanostructures on sapphire (100) substrates by reactive magnetron sputtering using Ti and Ru metal targets under different conditions. The surface morphology and structural properties of the as-deposited heteronanostructures were characterized using field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and selected-area electron diffractometry (SAED). The FESEM micrographs and XRD patterns indicated the growth of vertically aligned RuO2(001) nanotubes and twinned V-shaped RuO2(101) nanowedges (NWs) on top of R-TiO2 nanorods under different sputtering pressures. TEM and SAED characterizations of the V-shaped RuO2 NWs showed that the NWs are crystalline RuO2 with twin planes of (101) and twin direction of [ 01] at the V-junction.

scholarly journals Synthesis And Characterization Of SiO2, SnO2 And TiO2 Metal Oxide Shells Covering Cu2O Particles

2015 ◽  
Vol 60 (2) ◽  
pp. 1159-1163 ◽  
Author(s):  
Ri Yu ◽  
Jiyeon Yun ◽  
Yoojin Kim
Keyword(s):  
Synthesis And Characterization ◽  
Colloidal Solutions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ph Values ◽  
Coated Nanoparticles ◽  
Transmission Electron ◽  
The Stability ◽  
Over Time

Abstract In this work is described a means of improving the chemical stability of Cu2O@SiO2, Cu2O@SnO2 and Cu2O@TiO2 materials. The SiO2, SnO2 and TiO2 coated samples were stable from pH 3 to pH 10 for up to seven days. To determine the stability of the coated nanoparticles, and their colloidal solutions under acidic and basic conditions, colloidal nanoparticle solutions with various pH values were prepared and monitored over time. Details of the effect of variations in pH on the phase stability of core-shell type Cu2O were characterized using transmission electron microscopy and X-ray diffraction.

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