Pressure Dependent Magnetization of Arc Discharge Fe–C Soot

2016 ◽  
Vol 843 ◽  
pp. 96-100 ◽  
Author(s):  
S.A. Novopashin ◽  
N.A. Demin ◽  
A.V. Zaikovskii
Keyword(s):  
Magnetic Susceptibility ◽  
Arc Discharge ◽  
Iron Carbide ◽  
Carbon Matrix ◽  
Size Distribution Function ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Carbon Soot ◽  
Iron Iron ◽  
Means Of Transmission

This Composite Fe-C anode sputtering in a low-pressure arc discharge has been used to produce Fe-containing nanoparticles on a carbon matrix. Magnetic susceptibility as a function of background pressure has been measured. The data obtained showed the complex, no-monotonous dependency. The material synthesized at optimal pressure (maximal value of magnetic susceptibility) was investigated by means of transmission electron microscopy, X-ray diffraction and magnetometry. Size distribution function of iron containing nanoparticles has been measured. Chemical composition includes iron, iron carbide and carbon soot. Saturation magnetization have been measured and it was shown that the synthesized material is superparamagnetic. The physical processes resulting in the complex behavior of magnetic susceptibility are discussed.

Structural changes in titanium dioxide nanocrystals during plastic deformation

2005 ◽  
Vol 38 (5) ◽  
pp. 749-756 ◽  
Author(s):  
Ulrich Gesenhues
Keyword(s):  
Structural Changes ◽  
Crystal Size ◽  
Lower Layer ◽  
High Energy ◽  
Primary Crystal ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Hall Method ◽  
Means Of Transmission

The polygonization of 200 nm rutile crystals during dry ball-milling at 10gwas monitored in detail by means of transmission electron microscopy (TEM) and X-ray diffraction (XRD). The TEM results showed how to modify the Williamson–Hall method for a successful evaluation of crystal size and microstrain from XRD profiles. Macrostrain development was determined from the minute shift of the most intense reflection. In addition, changes in pycnometrical density were monitored. Accordingly, the primary crystal is disintegrated during milling into a mosaic of 12–35 nm pieces where the grain boundaries induce up to 1.2% microstrain in a lower layer of 6 nm thickness. Macrostrain in the interior of the crystals rises to 0.03%. The pycnometrical density, reflecting the packing density of atoms in the grain boundary, decreases steadily by 1.1%. The results bear relevance to our understanding of plastic flow and the mechanism of phase transitions of metal oxides during high-energy milling.

Characterization of Fe–Ni(C) nanocapsules synthesized by arc discharge in methane

1999 ◽  
Vol 14 (5) ◽  
pp. 1782-1790 ◽  
Author(s):  
X. L. Dong ◽  
Z. D. Zhang ◽  
S. R. Jin ◽  
W. M. Sun ◽  
X. G. Zhao ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Arc Discharge ◽  
Carbon Layer ◽  
Magnetization Measurement ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Energy Disperse Spectroscopy

Ultrafine Fe–Ni(C) particles of various compositions were prepared by arc discharge synthesis in a methane atmosphere. The particles were characterized by x-ray diffraction, transmission electron microscopy, energy disperse spectroscopy, chemical analysis, x-ray photoelectron spectroscopy, Mössbauer spectroscopy, and magnetization measurement. The carbon atoms solubilizing at interstitial sites in γ–(Fe, Ni, C) solution particles have the effects of forming austenite structure and changing microstructures as well as magnetic properties. A carbon layer covers the surface of Fe–Ni(C) particles to form the nanocapsules and protect them from oxidization. The mechanism of forming Fe–Ni(C) nanocapsules in the methane atmosphere was analyzed.

scholarly journals Effect of Carbon Additives on the Electrochemical Performance of Li4Ti5O12/C Anodes

Energies ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3941
Author(s):  
Irina Stenina ◽  
Ruslan Shaydullin ◽  
Tatiana Kulova ◽  
Anna Kuz’mina ◽  
Nataliya Tabachkova ◽  
...  
Keyword(s):  
Carbon Black ◽  
Electrochemical Performance ◽  
Rate Capability ◽  
Carbon Matrix ◽  
X Ray Diffraction ◽  
Discharge Rates ◽  
Transmission Electron ◽  
Carbon Additives ◽  
Promising Application ◽  
Carbon Replicas

The Li4Ti5O12/C composites were prepared by a hydrothermal method with in situ carbon addition. The influence of the morphology and content of various carbon materials (conductive carbon black, mesoporous carbon G_157M, and carbon replicas) on the electrochemical performance of the Li4Ti5O12/C composites was investigated. The obtained composites were characterized using X-ray diffraction, scanning electron microsopy, high-resolution transmission electron microscopy, thermogravimetric analysis, Raman spectroscopy, and N2 sorption-desorption isotherms. Morphology of the Li4Ti5O12/C composites depends on the carbon matrix used, while both morphology and the amount of carbon material have a great impact on the rate capability and cycling stability of the obtained composites. At low current densities, the Li4Ti5O12/C composite with 5 wt.% G_157M exhibits the highest discharge capacity, while at high charge-discharge rates, the Li4Ti5O12/carbon black composites show the best electrochemical performance. Thus, at ~0.1C, 5C, and 18C rates, the discharge capacities of the obtained Li4Ti5O12/C composites are 175, 120, and 70 mAh/g for G_157M, 165, 126, and 78 mAh/g for carbon replicas, and 173, 128, and 93 mAh/g for carbon black. After 100 cycles, their capacity retention is no less than 95%, suggesting their promising application perspective.

Engineering Iron-Based Nanoparticles Spatially Dispersed on Mesoporous Carbon and Its Catalytic Activity for the Direct Oxidization of Benzene to Phenol

NANO ◽  
2018 ◽  
Vol 13 (08) ◽  
pp. 1850094
Author(s):  
Qiang Sun ◽  
Long Liu ◽  
Yi-Ding Li ◽  
Zeng-Rong Wang ◽  
Xue Zhang
Keyword(s):  
Mesoporous Carbon ◽  
Molecular Diffusion ◽  
Carbon Matrix ◽  
Mesoporous Structure ◽  
X Ray Diffraction ◽  
Efficient Catalyst ◽  
X Ray ◽  
Transmission Electron ◽  
Benzene Hydroxylation ◽  
Iron Based

We report engineered iron-based nanoparticles supported on cagelike mesoporous carbon that leaves its most mesopores empty to retain an open pore network and are expected to be efficient catalyst with fast molecular diffusion/transportation. The nano-scale iron-based particle inlayed in mesoporous carbon catalyst was obtained via the introduction of N atoms as an anchor. Results of X-ray diffraction, N2 sorption and transmission electron microscopy showed that the cagelike mesoporous structure of the carbon matrix was retained during catalyst preparation and iron-based nanoparticles were spatially dispersed on the mesoporous carbon. Importantly, it was found that the obtained iron-based nanoparticles inlayed into mesoporous carbon with a low Fe loading of 1.26[Formula: see text]wt.% was an appropriate catalyst for the benzene hydroxylation to phenol using H2O2 as the oxidant. At a low temperature of 30∘C, 19.4% conversion to benzene and 14.6% phenol yield were obtained; in addition, the catalyst could be recycled at least four times.

Synthesis and thermodynamic evaluation of intermetallic Mg-Ni/Mg-Cu nanoscale powders

2009 ◽  
Vol 24 (8) ◽  
pp. 2503-2510 ◽  
Author(s):  
Jun-Peng Lei ◽  
Xing-Long Dong ◽  
Fu-Guo Zhao ◽  
Hao Huang ◽  
Xue-Feng Zhang ◽  
...  
Keyword(s):  
Physical Vapor Deposition ◽  
Arc Discharge ◽  
Heat Of Formation ◽  
Thermodynamic Evaluation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Physical Vapor Deposition Method ◽  
Effective Heat Of Formation ◽  
Good Agreement

Nanometer-sized intermetallic Mg-Ni and Mg-Cu compound powders were prepared by a physical vapor deposition method (arc discharge) and characterized by means of x-ray diffraction and transmission electron microscopy. Based on an empirical specific heat equation, the effective heat of formation and its temperature dependence were calculated to explain phase formation in nanoscale powders of the binary Mg-Ni and Mg-Cu systems. It is shown that theoretic calculations are in good agreement with the experimental observations.

Microstructure of Pyrolytic Carbon Matrix in Carbon/Carbon Composites after Graphitization

2007 ◽  
Vol 336-338 ◽  
pp. 1270-1273 ◽  
Author(s):  
Wan Chang Sun ◽  
He Jun Li ◽  
Shou Yang Zhang ◽  
Yong Huang
Keyword(s):  
Polarized Light ◽  
Carbon Matrix ◽  
Pyrolytic Carbon ◽  
Interplanar Distance ◽  
Carbon Composites ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Before And After ◽  
The Matrix ◽  
Microstructure Parameters

The morphologies and textures of the pyrolytic carbon matrix in 2D-C/C composites after graphitization were investigated by means of polarized light microscope (PLM) and high resolution transmission electron microscope (HRTEM). The microstructure parameters of the pyrolytic carbon matrix before and after graphitization were characterized with X-ray diffraction (XRD) technology. It was found that the interplanar distance of (002) planes (d002) of pyrolytic carbon matrix decreases, and the microcrystalline stack height (LC) increases after graphitization. Graphitization treatment resulted in a coarsening of the surface texture and in the formation of circumferential cracks within the matrix. The lattice fringes of the pyrolytic carbon matrix are continuous and longer in each domain and the (002) peak spot is smaller and more intense after graphitization.

TEM Analysis on Bio-Functional Gradient Hydroxyapatite/ZrO2 Coatings

2007 ◽  
Vol 336-338 ◽  
pp. 1676-1678
Author(s):  
Cheng Yun Ning ◽  
Ying Jun Wang ◽  
Xiao Feng Chen ◽  
Jian Dong Ye ◽  
Gang Wu ◽  
...  
Keyword(s):  
Net Energy ◽  
X Ray Diffraction ◽  
Tem Analysis ◽  
X Ray ◽  
Amorphous Phases ◽  
Functional Gradient ◽  
Transmission Electron ◽  
Gradient Coatings ◽  
Means Of Transmission ◽  
Sprayed Coatings

In the present study, bioactive functional gradient coatings were prepared using net-energy controlled plasma spraying technology. The microstructure and phases of the bioactive functional gradient coating were examined by means of transmission electron microscope, scanning electron microscopy and X-ray diffraction. The results revealed that: (1) as-sprayed coatings contained a large amount of amorphous phases and some nano-sized HA crystals formed during rapid solidification, (2) surface of the coating was very rough with different-sized micropores, and the gradient layer was much denser which firmly bonded to the substrate without gaps and obvious interface between the coating and the substrate

Scalable Production of Carbon Encapsulated Ni Nanoparticles by Water Arc Discharge: Structural and Magnetic Properties

2005 ◽  
Vol 23 ◽  
pp. 87-90 ◽  
Author(s):  
K.H. Ang ◽  
I. Alexandrou ◽  
N.D. Mathur ◽  
R. Lacerda ◽  
I.Y.Y. Bu ◽  
...  
Keyword(s):  
Particle Size ◽  
Magnetic Properties ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Arc Discharge ◽  
Narrow Particle Size Distribution ◽  
Ni Nanoparticles ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Water Container

An electric arc discharge in de-ionised water between a solid graphite cathode and an anode made by compressing Ni and C containing powders in a mass ratio of Ni:C = 7:3 was used here to prepare carbon encapsulated Ni nanoparticles in the form of powder suspended in water. The morphology of the produced material was analysed using high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD). The magnetic properties of the samples were determined using a Princeton vibrating sample magnetometer (VSM). Collection of the powder produced from different depths in the water container has proved to be an effective method for obtaining samples with narrow particle size distribution. Further material purification by dry NH4 plasma etching was used to remove the amorphous carbon content of the samples. XRD and HRTEM analysis showed that the material synthesized is fcc Ni particles with mean particle size ranging from 14 to 30 nm encapsulated in 2 to 5 graphitic cages. The data suggests that the process reported has the ability to mass-produce carbon encapsulated ferromagnetic nanoparticles with desired particle size distribution, and hence with controlled size-dependent magnetic properties.

The Microstructure of Fe7C3 Formed at 300°C by Plasma Enhanced Chemical Vapor Deposition (PECVD)

1993 ◽  
Vol 313 ◽  
Author(s):  
H. Siriwardane ◽  
P. Fraundorf ◽  
J.W. Newkirk ◽  
O.A. Pringle ◽  
W.J. James
Keyword(s):  
Oxidation Process ◽  
Iron Carbide ◽  
Chemical Vapor ◽  
Carbon Films ◽  
Corrosion And Wear ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Iron Phase ◽  
Diffraction Patterns

Thin iron carbide films were prepared by introducing iron penta carbonyl (FeCO5) and hydrogen (H2) into a glow discharge. The films are of potential interest in corrosion and wear resistant applications. X-ray diffraction data of films (≈ 7000 Å thick) deposited on glass at 300°C evidenced only Fe7C3. Thinner films were required for examination by analytical and high resolution transmission electron Microscopy. Therefore, two sets of films (“thin” < 200 Å and “thick” ≈ 800 Å) were plasma-deposited on carbon or holey carbon films supported on copper grids. The thin TEM specimens exhibited a fine texture and gave rise to ring diffraction patterns, whereas the thick TEM specimens evidenced two types of structure: (i) half-Micron sized grains separated from one another by 1–2 Microns on the support, although sometimes interconnected by single crystal platelets and (ii) 300 Å grapelike clumps of 100–200 Å crystals, each individually surrounded by a 50 Å non-crystalline coating. The latter structure may result from a post-formation oxidation process which expels carbon from the iron phase into grain boundaries.

AC Magnetic Susceptibility Study in Co/Au Nanoparticles

2015 ◽  
Vol 233-234 ◽  
pp. 497-500 ◽  
Author(s):  
Pavol Hrubovčák ◽  
Adriana Zeleňáková ◽  
Vladimír Zeleňák ◽  
Jana Michalíková
Keyword(s):  
Magnetic Susceptibility ◽  
Relaxation Process ◽  
Au Nanoparticles ◽  
Theoretical Models ◽  
Particle Interactions ◽  
Ac Magnetic Susceptibility ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Susceptibility Study ◽  
Average Size

In this work we report the study of magnetic relaxation process presented in the bimetallic Co/Au nanoparticles prepared utilizing the reverse micelle method. Structural analysis of the system using synchrotron X-ray diffraction and transmission electron microscopy documented individual nanocrystalline particles of average size about 7 nm. Magnetic properties of the particles were examined by ac magnetic susceptibility measurements at temperature range 2 – 300 K at different frequencies of magnetic field. The relaxation process was revealed at temperature about 6 K. Application of several theoretical models on experimental data of magnetic susceptibility confirmed strong inter-particle interactions and novel superspin glass state in the nanoparticle system at low temperatures.

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