Transmission electron microscopy study of barium hexaferrite formation from barium carbonate and hematite

1999 ◽  
Vol 14 (9) ◽  
pp. 3647-3652 ◽  
Author(s):  
Hanns P. Steier ◽  
Joaquin Requena ◽  
José S. Moya
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Barium Carbonate ◽  
Average Particle Size ◽  
Exothermic Reaction ◽  
Barium Hexaferrite ◽  
Microscopy Study ◽  
Average Particle ◽  
Contact Points ◽  
Transmission Electron

The formation of barium hexaferrite from stoichiometric mixtures of BaCO3 and Fe2O3 has been investigated by means of differential thermal analysis and thermogravimetry, x-ray diffraction, and transmission electron microscopy–energy dispersive spectrometry. The first step, which implies decarbonatation and monoferrite formation, includes the formation of various intermediate compounds, which are formed at contact points between BaCO3 and Fe2O3 grains, and implies diffusion of both species. In the second step, barium hexaferrite is formed at interfaces between monoferrite and iron oxide mainly by diffusion of barium through the BF6 lattice into the hematite lattice. This exothermic reaction process leads to nonagglomerated pseudohexagonal platelets with an average particle size very close to the one of the starting powder mixture (∼1 μm).

Synthesis and Characterization of Water-Soluble Monolayer-Protected Gold Nanoparticles

2011 ◽  
Vol 415-417 ◽  
pp. 617-620 ◽  
Author(s):  
Yan Su ◽  
Ying Yun Lin ◽  
Yu Li Fu ◽  
Fan Qian ◽  
Xiu Pei Yang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Particle Size ◽  
Gold Nanoparticles ◽  
Average Particle Size ◽  
Water Soluble ◽  
Synthesis And Characterization ◽  
Average Particle ◽  
Transmission Electron

Water-soluble gold nanoparticles (AuNPs) were prepared using 2-mercapto-4-methyl-5- thiazoleacetic acid (MMTA) as a stabilizing agent and sodium borohydride (NaBH4) as a reducing agent. The AuNPs product was analyzed by transmission electron microscopy (TEM), UV-vis absorption spectroscopy and Fourier transform infrared spectroscopy (FTIR). The TEM image shows that the particles were well-dispersed and their average particle size is about 5 nm. The UV-vis absorption and FTIR spectra confirm that the MMTA-AuNPs was stabilized by the carboxylate ions present on the surface of the AuNPs.

Catalytic Reduction of Nitrobenzene Using Silver Nanoparticles Embedded Calcium Alginate Film

2019 ◽  
Vol 19 (11) ◽  
pp. 7487-7492 ◽  
Author(s):  
Supriya ◽  
Jayanta Kumar Basu ◽  
Sonali Sengupta
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Silver Nanoparticles ◽  
Sodium Borohydride ◽  
Calcium Alginate ◽  
Catalytic Reduction ◽  
Average Particle Size ◽  
Catalyst Loading ◽  
Average Particle ◽  
Transmission Electron

Synthesis of silver nanoparticles embedded on calcium alginate film and the catalytic property of this film in the reduction of nitrobenzene with sodium borohydride are demonstrated in this work. Natural polymer alginate acts as effective reducing and stabilizing agent in synthesis of silver nanoparticles. Effect of different parameters on the preparation of silver nanoparticles, such as, temperature, concentration of silver precursor and heating time was investigated. As-prepared silver nanoparticles were characterized by transmission electron microscopy, scanning electron microscopy, UV-Vis spectrometry, and atomic absorption spectrometry. Transmission electron microscopy analysis con-firms the formation of silver nanoparticles with particles size range of 3–19 nm and average particle size was found to be 10±4 nm. Effect of concentration of nitrobenzene and sodium borohydride, catalyst loading and temperature on the catalytic reduction of nitrobenzene was studied. Reusability of catalyst was examined in this reduction reaction and the catalyst shows good activity up to 10th run.

The Aggregation Study and Characterization of Silver Nanoparticles

2017 ◽  
Vol 263 ◽  
pp. 165-169
Author(s):  
Silvia Chowdhury ◽  
Faridah Yusof ◽  
Nadzril Sulaiman ◽  
Mohammad Omer Faruck
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Particle Size ◽  
Silver Nanoparticles ◽  
Absorption Spectrum ◽  
Average Particle Size ◽  
Average Particle ◽  
Transmission Electron ◽  
Vis Spectroscopy

In this article, we have studied the process of silver nanoparticles (AgNPs) aggregation and to stop aggregation 0.3% Polyvinylpyrrolidone (PVP) was used. Aggregation study carried out via UV-vis spectroscopy and it is reported that the absorption spectrum of spherical silver nanoparticles were found a maximum peak at 420 nm wavelength. Furthermore, Transmission Electron Microscopy (TEM) were used to characterized the size and shape of AgNPs, where the average particle size is around 10 to 25 nm in diameter and the AgNPs shape is spherical. Next, Dynamic Light Scattering (DLS) were used, owing to observed size distribution and self-correlation of AgNPs.

Biosynthesis and Characterization of Copper Nanoparticles Using a Bioflocculant Extracted from Alcaligenis faecalis HCB2

2019 ◽  
Vol 11 (11) ◽  
pp. 1064-1070 ◽  
Author(s):  
Nkosinathi G. Dlamini ◽  
Albertus K. Basson ◽  
V. S. R. Rajasekhar Pullabhotla
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Copper Nanoparticles ◽  
Average Particle Size ◽  
Thermo Gravimetric Analysis ◽  
Average Particle ◽  
Gravimetric Analysis ◽  
X Ray ◽  
Transmission Electron ◽  
Ft Ir

Bioflocculant from Alcaligenis faecalis HCB2 was used in the eco-friendly synthesis of the copper nanoparticles. Nanoparticles were characterized using a scanning electron microscope (SEM), transmission electron microscopy (TEM), UV-visible spectroscopy, thermo gravimetric analysis (TGA) and Fourier Transform Infrared Spectroscopy (FT-IR). The transmission electron microscopy images showed close to spherical shapes with an average particle size of ∼53 nm. Energy-dispersive X-ray spectroscopy analysis confirmed the presence of the Cu nanopartilces and also the other elements such as O, C, P, Ca, Cl, Na, K, Mg, and S originated from the bioflocculant. FT-IR results showed the presence of the –OH and –NH2 groups, aliphatic bonds, amide and Cu–O bonds. Powder X-ray diffraction peaks confirmed the presence of (111) and (220) planes of fcc structure at 2 of 33° and 47° respectively with no other impurity peaks.

DIELECTRIC PROPERTIES OF ULTRAFINE Zn-DOPED CaCu3Ti4O12 CERAMIC

2012 ◽  
Vol 02 (01) ◽  
pp. 1250007 ◽  
Author(s):  
LAXMAN SINGH ◽  
U. S. RAI ◽  
K. D. MANDAL ◽  
MADHU YASHPAL
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Room Temperature ◽  
Single Phase ◽  
Average Particle Size ◽  
Average Particle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Sintered Powder

Ultrafine powder of CaCu2.80Zn0.20Ti4O12 ceramic was prepared using a novel semi-wet method. DTA/TG analysis of dry powder gives pre-information about formation of final product around 800°C. The formation of single phase was confirmed by X-ray diffraction analysis. The average particle size of sintered powder of the ceramic obtained from XRD and Transmission electron microscopy was found 59 nm and 102 nm, respectively. Energy Dispersive X-ray studies confirm the stoichiometry of the synthesized ceramic. Dielectric constant of the ceramic was found to be 2617 at room temperature at 1 kHz.

Studies on conducting nanocomposite with gallium nitride–doped ferrite, part-II

2017 ◽  
Vol 231 (1) ◽  
pp. 53-63
Author(s):  
Rajani Indrakanti ◽  
V Brahmaji Rao ◽  
C Udaya Kiran
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Gallium Nitride ◽  
Crystallite Size ◽  
Average Particle Size ◽  
Average Particle ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Electron

This article (a sequel to part-I that appeared earlier in the same journal) presents synthesis and characterisation details of conducting PPY-nanocomposite obtained from gallium nitride–doped ferrite and polypyrrole. The GaN-doped ferrite is synthesised by sol–gel method. GaNFe2O3f-PPY composites are prepared by impregnation technique. Using the SciFinder software we could not trace any report in the literature for this synthesised Ga(2x + 2)NFe2(49 − x)O3-PPY nanocomposites. The doped nanoferrite is combined with polypyrrole, an intrinsic conducting polymer, in three proportions by percentage (70%:30%), (90%:10%) and (97%:3%), to obtain two series each of three compositions for the conducting PPY-nanocomposite. The synthesised polymer composites are characterised by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, selected area electron diffraction, energy dispersive X-ray analysis and Fourier transform infrared spectroscopy. From our studies, it has been observed that the crystallite size of nanocomposites is decreased when compared to crystallite size of GaNFe2O3. The average particle size from histogram is in good agreement with Debye–Scherrer formula calculations. The scanning electron microscopy and transmission electron microscopy micrograms reveal that the particles are varying with the values of X and the percentage of PPY. The shapes observed are Globules,Tetrahedron,Nanorods of short and long lengths. The GaNFe2O3-PPY composites’ spectra revealed the shift in the band in comparison with the PPY spectra. Also, the wavelength is decreased, and vibrational frequency is increased.

Analysis of the Promoter-Catalyst interaction between Mn and Rh by Transmission Electron Microscopy

2014 ◽  
Vol 7 (1) ◽  
Author(s):  
B. Graham ◽  
R.F. Klie
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Particle Size ◽  
Average Particle Size ◽  
Lattice Parameter ◽  
Average Particle ◽  
Fischer Tropsch ◽  
Transmission Electron ◽  
Three Samples ◽  
Promoter Interaction

In the hope of optimizing the Fischer-Tropsch mechanism to produce cleaner ethanol, the catalyst- promoter interaction between rhodium and manganese was examined by transmission electron microscopy. Three samples were analyzed on a carbon nanotube (CNT) substrate with 3 wt% rhodium (3%Rh/CNT), 1% manganese with 3 wt% rhodium (1%Mn/3% Rh/CNT), and 2% manganese with 3 wt% rhodium (2% Mn/3% Rh/CNT). The average particle size were found to be (1.9 ± 0.6) nm, (2.1 ± 0.5) nm, and (3.2 ± 0.6) nm, respectively. An increase in particle size indicates that the rhodium and manganese are interacting. The lattice parameter for rhodium were also determined to be (4.1 ± 0.1) Å, (4.2 ± 0.1) Å, and (3.8 ± 0.1) Å, respectively. The decrease in lattice parameter in the 2%Mn/3%Rh/CNT sample was most likely due to a change in the crystal structure of the rhodium particles as a result of the interaction between the manganese and rhodium.

scholarly journals Surface Modification of Carbon Nanofibers and Graphene Platelets Mixtures by Plasma Polymerization of Propylene

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Carlos Andrés Covarrubias-Gordillo ◽  
Florentino Soriano-Corral ◽  
Carlos Alberto Ávila-Orta ◽  
Victor Javier Cruz-Delgado ◽  
María Guadalupe Neira-Velázquez ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Raman Spectroscopy ◽  
Carbon Nanofibers ◽  
Plasma Polymerization ◽  
Carbon Nanoparticles ◽  
Average Particle Size ◽  
Average Particle ◽  
Transmission Electron ◽  
Graphene Platelets

Carbon nanofibers (CNFs), graphene platelets (GPs), and their mixtures were treated by plasma polymerization of propylene. The carbon nanoparticles (CNPs) were previously sonicated in order to deagglomerate and increase the surface area. Untreated and plasma treated CNPs were analyzed by dynamic light scattering (DLS), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and thermogravimetric analysis (TGA). DLS analysis showed a significant reduction of average particle size, due to the sonication pretreatment. Plasma polymerized propylene was deposited on the CNPs surface; the total amount of polymerized propylene was from 4.68 to 6.58 wt-%. Raman spectroscopy indicates an increase in the sp3 hybridization of the treated samples, which suggest that the polymerized propylene is grafted onto the CNPs.

Preparation of an Amphiphilic Magnetic Copolymer Microspheres

2014 ◽  
Vol 881-883 ◽  
pp. 846-849
Author(s):  
Zai Man Liu ◽  
Yun Liu ◽  
Peng Zhang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Average Particle Size ◽  
Water Soluble ◽  
Magnetic Microspheres ◽  
Average Particle ◽  
Water Medium ◽  
Vibrating Sample Magnetometer ◽  
Transmission Electron ◽  
Average Size

The magnetic polymer microspheres were synthesized by copolymerization of styrene with a water-soluble polyurethane macromonomer in the presence of Fe3O4in ethanol/water medium. The structure of copolymer was determined by FTIR spectroscopy. The morphology and the average size of magnetic microspheres were characterized by transmission electron microscopy. The magnetic properties were recorded with a vibrating sample magnetometer. The results show that the magnetic microspheres had an average particle size of 500nm. The magnetic microspheres have super paramagnetic, enhanced hydrophilicity and the characteristics of simple and rapid magnetic separation. The magnetic susceptibility was 3.898×10-5emu/(Oe·g) and the saturation magnetization was 41.122 emu/g.

IMPACT OF SURFACTANTS ON PHYSICAL PROPERTIES OF BaTiO3 NANOPARTICLES

2013 ◽  
Vol 12 (01) ◽  
pp. 1350003 ◽  
Author(s):  
R. VIJAYALAKSHMI ◽  
V. RAJENDRAN
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Average Particle Size ◽  
Ammonium Bromide ◽  
Average Particle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Electron

Nanocrystalline BaTiO3 particles of about 20–35 nm have been successfully synthesized by using cationic, anionic and nonionic surfactants such as cetyltrimethyl ammonium bromide (CTAB), sodium dodecyl sulphate (SDS) and poly ethylene glycol (PEG) via hydrothermal method. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-Vis absorption spectroscopy and photoluminescence (PL) spectroscopy. The average particle size, measured by powder X-ray diffraction was determined to be 20–35 nm and was confirmed by transmission electron microscopy. Spherical-like morphologies were obtained by scanning electron microscopy (SEM) analysis. Optical properties of products were investigated by ultraviolet-visible (UV-Vis) absorption and PL spectroscopies.

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