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.

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.

Microstructure of Carbon Encapsulated Superparamagnetic Co Nanoparticles

2001 ◽  
Vol 704 ◽  
Author(s):  
Xiang-Cheng Sun ◽  
J. Reyes-Gasga ◽  
X. L. Dong
Keyword(s):  
Electron Microscopy ◽  
Arc Discharge ◽  
Stacking Faults ◽  
Good Evidence ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Lattice Images ◽  
Co Nanoparticles ◽  
Discharge Method

AbstractCarbon encapsulated magnetic Co nanoparticles have been synthesized by modified arc-discharge method. Both high-resolution transmission electron microscopy (HREM) and powder x-ray diffraction (XRD) profiles reveal the presence of 8-15nm diameter crystallites coated with 1-3 carbon layers. Specially, HREM images indicate that the intimate and contiguous carbon fringe around those Co nanoparticles is good evidence for complete encapsulation by carbon shell layers. The encapsulated phases are identified as hcp (α)-Co, fcc (β)-Co and cobalt carbide (Co3C) nanocrystals by using x-ray diffraction, electron diffraction and energy dispersive x-ray analysis. However, some fcc (β)-Co particles with a significant fraction of stacking faults are observed by HREM and confirmed by means of numerical Fourier transform (FFT) of HREM lattice images. In particular, the carbon encapsulation formation and growth mechanism are also reviewed.

Structural Transitions in Titanium/Amorphous-Silicon Multilayers

1989 ◽  
Vol 163 ◽  
Author(s):  
E. Ma ◽  
L.A. Clevenger ◽  
C.V. Thompson ◽  
R.R. DeAvillez ◽  
K.N. Tu
Keyword(s):  
Thin Films ◽  
Exothermic Reaction ◽  
Heat Of Formation ◽  
Structural Transitions ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Calorimetric Analysis ◽  
Cross Sectional ◽  
X Ray ◽  
Transmission Electron

We report a quantitative investigation of silicidation in Ti/amorphous-Si thin-films using Differential Scanning Calorimetry (DSC), thin-film X-ray diffraction and Cross-sectional Transmission Electron Microscopy (XTEM). Multilayered thin films were used to facilitate calorimetric observation of the heat released or absorbed at many reacting interfaces. It is shown that calorimetric analysis, combined with structural analysis using X-ray diffraction and XTEM, is effective in providing both kinetic and thermodynamic information about interdiffusion reactions in thin films. The present paper describes experimental results for multilayers with an atomic concentration ratio of 1 Ti to 2 Si and modulation periods ranging from 10 to 60 nm. A thin amorphous titanium suicide layer was found to exist between the as-deposited Ti and a-Si layers. Heating the multilayer film caused the amorphous Ti-silicide to grow over a broad temperature range by an exothermic reaction. An endothermic relaxation occurs during the late stage of amorphous suicide growth. Heating to temperatures over 800K causes C49-TiSi2 to form at the a-si1icide/a-Si interface. Temperatures at which all the above structural transitions occur vary with modulation period. Analysis of the DSC data indicates an activation energy of 3.1 eV for the formation of C49-TiSio, which is attributed to both the nucleation and the early growth of the suicide. The heat of formation for C49-TiSi2 from a reaction of a-silicide and a-Si was found to be -30±5KJ/mol. Nucleation appears to be the controlling step in C49-TiSi2 formation.

Microstructure and Properties of CoSi2 Thin Films on (100) Silicon by Laser Physical Vapor Deposition

1992 ◽  
Vol 285 ◽  
Author(s):  
P. Tiwari ◽  
R. Chowdhury ◽  
J. Narayan
Keyword(s):  
Thin Films ◽  
Vapor Deposition ◽  
Physical Vapor Deposition ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microstructure And Properties ◽  
Transmission Electron ◽  
Substrate Temperatures ◽  
Deposited Films

ABSTRACTLaser physical vapor deposition (LPVD) has been used to deposit thin CoSi2 films on (001)silicon at different substrate temperatures ranging from room temperature to 600°C. Particulate-free silicide thin films were characterized by X-ray diffraction, Rutherford backscattering, and high resolution transmission electron microscopy. We have found that films deposited at 200°C and below are amorphous; 400°C deposited films are polycrystalline whereas films deposited at 600°C are of epitaxial nature. The Effect of subsequent annealing on resistivity of room-temperature deposited thin films has been investigated. The resistivity value decreases to less than 15 μΩcm after annealing making these films suitable for microelectronics applications. The correlation between microstructure and properties of these films are discussed.

Microstructure and Magnetic Properties of Fe(C) and Fe(O) Nanoparticles

2001 ◽  
Vol 704 ◽  
Author(s):  
Xiang-Cheng Sun ◽  
N. Nava ◽  
J. Reyes-Gasga
Keyword(s):  
Room Temperature ◽  
Arc Discharge ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Hrtem Observation ◽  
Average Grain Size ◽  
Fe Nanoparticles ◽  
Carbon Coated

AbstractTwo types of iron (Fe) nanoparticles, carbon-coated Fe nanoparticles (Fe(C)) and pure α-Fe nanoparticles that coated with oxide layers (Fe(O)), have been successfully synthesized using modified graphite arc-discharge method. X-ray diffraction (XRD), high-resolution transmission electron microscopy (HREM) and electron diffraction (SAED) analysis have been used to characterize these distinct structural morphologies. It is indicated that those two Fe nanoparticles have an average grain size of 15-20nm. The presence of carbon encapsulated α-Fe, γ-Fe and Fe3C phases are clearly identified by X-ray diffraction and SAED patterns in those Fe(C) particles. However, the evidence of pure α-Fe nanocrystal coated with oxide layer is also revealed by HR-TEM images and SAED patterns in these Fe(O) particles.Mössbauer spectra and hyperfine magnetic fields at room temperature for the assemblies of Fe(C) and Fe(O) nanoparticles further confirm their distinct nanophases that detected by XRD analysis and HRTEM observation. Specially, the assemblies of Fe(O) nanoparticles exhibit ferromagnetic properties at room temperature due to the stronger interparticle interaction and bigger magnetocrystalline anisotropy effects among these Fe(O) nanoparticles. Moreover, modified superparamagnetic relaxation is observed in the assemblies of Fe(C) nanoparticles, which is attributed to the nanocrystalline nature of the carbon-coated nanoparticles.

scholarly journals The optical properties of C\Mg, nano-rods produced by the explosion wire technique

2021 ◽  
Vol 2114 (1) ◽  
pp. 012041
Author(s):  
Nada. K. Hussein ◽  
S.J. Kadhem
Keyword(s):  
Image Analysis ◽  
Optical Properties ◽  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Energy Gap ◽  
Arc Discharge ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Nano Rods

Abstract The aim of this research is to study the optical properties of carbon-magnesium plasma resulting from arc discharge with explosive wire technique, where the energy gap of each of carbon and magnesium and the carbon-magnesium bond for three values of the wire exploding current (50,75,100 amperes) was studied. It was found that the energy gap for each of carbon and magnesium decreases with increasing the current, the X-ray diffraction of magnesium and the carbon-magnesium suspension was studied, and FTIR of the carbon-magnesium suspended carbon was studied for three values of the exploding current (50, 75, 100 amperes) and the type of bonds for carbon and magnesium was determined. To obtain deeper insight about the morphology and size distribution of the nano rods obtained from the explosion of a magnesium strip in a carbon suspension images obtained from transmission electron microscope (TEM) image analysis confirmed that the formed nanomaterial is rod-shaped.

Phase formation sequence induced by deposition temperatures in Nb/Si multilayers

1998 ◽  
Vol 13 (5) ◽  
pp. 1373-1378 ◽  
Author(s):  
Ming Zhang ◽  
W. K. Wang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Phase Formation ◽  
Room Temperature ◽  
Heat Of Formation ◽  
Silicide Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Amorphous Phases ◽  
Transmission Electron

The phase formation sequence in Nb/Si multilayers formed at different deposition temperatures was investigated by x-ray diffraction (XRD) and transmission electron microscopy (TEM). The amorphous phases were found to form in Nb/Si multilayers deposited at room temperature and 560 °C, but the compositions of these two amorphous phases were different. The crystalline Nb3Si and Nb5Si3 were formed in Nb/Si multilayers deposited at 180–500 °C. The interfacial energy and modified heat of formation are adopted to explain our obtained results. The occurrence of crystalline Nb5Si3, NbSi2, and amorphous silicide phase was found when the Nb/Si multilayers with Nb3Si phase were annealed at 550 °C, while only NbSi2 was found to form when annealing this sample at 700 °C. The mobility of Si takes an important role in phase formation in Nb/Si multilayers.

scholarly journals Effects of Increasing Electrodes on CNTs Yield Synthesized by Using Arc-Discharge Technique

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Samy Yousef ◽  
A. Khattab ◽  
T. A. Osman ◽  
M. Zaki
Keyword(s):  
Electron Microscope ◽  
Arc Discharge ◽  
X Ray Diffraction ◽  
Multiwalled Carbon ◽  
X Ray ◽  
Pure Graphite ◽  
Transmission Electron ◽  
Multiple Electrodes ◽  
Fully Automatic ◽  
Single Plasma

A new design of fully automatic system was built up to produce multiwalled carbon nanotube (MWCNT) using arc discharge technique in deionized water and extra pure graphite multiple electrodes (99.9% pure). The goal of the experimental research is to determine the yield of CNT in two different cases: (a) single plasma electrodes and (b) multiplasma electrodes, particularly 10 electrodes. The experiments were performed at constant parameters (75 A, 238 V). The obtained CNT was examined by scanning electron microscope (SEM), transmission electron microscope (HRTEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The results showed that the produced CNT is of type MWCNT, with a diameter of 5 nm, when using multiplasma electrodes and 13 nm when using single plasma electrodes. The yield of MWCNT was found to be 320% higher in case of comparing multielectrodes to that of single plasma electrodes. Under the experimental test conditions, a yield of 0.6 g/hr soot containing 40% by mass nanotube was obtained in case of single plasma electrodes and above 60% in case of multiplasma electrodes.

Thin-film compound phase formation at Fe–Ge and Cr–Ge interfaces

2003 ◽  
Vol 18 (8) ◽  
pp. 1900-1907 ◽  
Author(s):  
O. M. Ndwandwe ◽  
C. C. Theron ◽  
T. K. Marais ◽  
R. Pretorius
Keyword(s):  
Thin Film ◽  
Phase Formation ◽  
Rutherford Backscattering Spectrometry ◽  
Heat Of Formation ◽  
Miedema Model ◽  
Formation Model ◽  
X Ray Diffraction ◽  
X Ray ◽  
Effective Heat Of Formation ◽  
Transformation Enthalpy

Phase formation was studied in the Fe–Ge and Cr–Ge thin-film systems by means of Rutherford backscattering spectrometry and x-ray diffraction. In the Fe–Ge system, FeGe was the first phase to form while in the Cr–Ge system, Cr11Ge8 was found to form first. The results are compared with the predictions of the effective heat of formation model. Heats of formation were calculated using the Miedema model. The effect of the transformation enthalpy term ΔHtr, used to convert a semiconducting element into a hypothetical metallic one in the Miedema model, is also discussed.

Synthesis and Analysis of Mn3O4@Graphene Nanocomposites for Supercapacitors

2017 ◽  
Vol 26 (1) ◽  
pp. 096369351702600 ◽  
Author(s):  
Mingfu Zhu ◽  
Ruimin Fu
Keyword(s):  
Arc Discharge ◽  
Electrochemical Behaviour ◽  
Electronic Conduction ◽  
Graphene Sheets ◽  
X Ray Diffraction ◽  
Graphene Nanocomposites ◽  
X Ray ◽  
Transmission Electron ◽  
Morphology And Structure ◽  
Discharge Method

An easy arc discharge method was developed to synthesize nanocomposites composed of Mn3O4 nanoparticles loaded on graphene sheets. The morphology and structure of the obtained nanocomposites were analysed via X-ray diffraction, Raman spectroscopy, and transmission electron microscopy. The electrochemical behaviour of the product was evaluated via cyclic voltammetry and alternating current impedance. Results showed that Mn3O4 was dispersed homogeneously on the surface of graphene. The supercapacitor constructed by graphene/Mn3O4 as the positive electrode showed both high capacitance and good electronic conduction, which may lead to the development of nanocomposites with great potential for applications in biosensors and electrode material analysis.

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