Face-centered-cubic titanium: An artifact in titanium/aluminum multilayers

1999 ◽  
Vol 14 (5) ◽  
pp. 1977-1981 ◽  
Author(s):  
J. Bonevich ◽  
D. van Heerden ◽  
D. Josell
Keyword(s):  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
Reflection And Transmission ◽  
Multilayer Systems ◽  
Composition Modulation ◽  
Transmission Electron ◽  
Titanium Aluminum ◽  
High Resolution Tem ◽  
Face Centered

The present investigation is the first comprehensive comparative study of x-ray diffraction (XRD) and transmission electron microscopy (TEM) results to address the important issue of fcc Ti formation in nanoscale multilayers. Ti/Al multilayers with 7.2 and 5.2 nm composition modulation wavelengths were studied by reflection and transmission XRD as well as transmission electron diffraction (ED), high-resolution TEM, and energy-filtered TEM. Previous reports have claimed deposition of fcc Ti in multilayer systems. Our results demonstrate that the Ti in Ti/Al multilayers deposits in the hcp form and that fcc Ti is merely an artifact of producing specimens for cross-sectional TEM.

Thermal Stability and Failure Mechanisms of Au/Tiw(N)/Si and Au/TiW(N)/Si02/Si Systems

1996 ◽  
Vol 427 ◽  
Author(s):  
C. R. Chen ◽  
L. J. Chen
Keyword(s):  
Thermal Stability ◽  
Failure Mechanisms ◽  
Cubic Phase ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Single Face ◽  
Face Centered ◽  
The Stability ◽  
Ar Gas

AbstractThermal stability and failure mechanisms of Au/TiW(N)/Si and Au/TiW(N)/SiO2/Si systems have been studied by both conventional and high-resolution transmission electron microscopy, X- ray diffraction and Auger electron spectroscopy. For films deposited in Ar gas containing 20% N2, a single face-centered-cubic phase was the only crystalline phase detected to form. The samples were found to remain stable after annealing at 700 °C for 30 min. The stability temperature for Au/TiW(N)(Ar:N2=80:20)/SiO2/Si samples was found to be higher than those of Au/TiW(N) (Ar:N2=90:10)/SiO2/Si and Au/TiW/SiO2/Si samples.

Structural, morphological, and magnetic study of nanocrystalline cobalt-copper powders synthesized by the polyol process

1995 ◽  
Vol 10 (6) ◽  
pp. 1546-1554 ◽  
Author(s):  
G.M. Chow ◽  
L.K. Kurihara ◽  
K.M. Kemner ◽  
P.E. Schoen ◽  
W.T. Elam ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Copper Powders ◽  
Face Centered ◽  
Increasing Temperature ◽  
X Ray Absorption

Nanocrystalline CoxCu100−x (4 ⋚ x ⋚ 49 at. %) powders were prepared by the reduction of metal acetates in a polyol. The structure of powders was characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), extended x-ray absorption fine structure (EXAFS) spectroscopy, solid-state nuclear magnetic resonance (NMR) spectroscopy, and vibrating sample magnetometry (VSM). As-synthesized powders were composites consisting of nanoscale crystallites of face-centered cubic (fcc) Cu and metastable face-centered cubic (fcc) Co. Complementary results of XRD, HRTEM, EXAFS, NMR, and VSM confirmed that there was no metastable alloying between Co and Cu. The NMR data also revealed that there was some hexagonal-closed-packed (hcp) Co in the samples. The powders were agglomerated, and consisted of aggregates of nanoscale crystallites of Co and Cu. Upon annealing, the powders with low Co contents showed an increase in both saturation magnetization and coercivity with increasing temperature. The results suggested that during preparation the nucleation of Cu occurred first, and the Cu crystallites served as nuclei for the formation of Co.

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.

Microstructure and Tribological Behavior of Cr-DLC Nanocomposite Films

2001 ◽  
Vol 697 ◽  
Author(s):  
V. Singh ◽  
J.C. Jiang ◽  
E.I. Meletis
Keyword(s):  
Nanocomposite Films ◽  
Face Centered Cubic ◽  
Cr Content ◽  
Transmission Electron ◽  
Diamondlike Carbon ◽  
High Resolution Tem ◽  
Pin On Disc ◽  
The Coefficient Of Friction ◽  
High Bias ◽  
Face Centered

AbstractCr-diamondlike carbon (Cr-DLC) nanocomposite films with the Cr content varying up to 27 at. % were synthesized by reactive magnetron sputtering. Their microstructure and tribological properties were studied using transmission electron microscopy (TEM) and pin-on-disc experiments, respectively. Electron diffraction and high- resolution TEM studies show that the films, with ∼ 9 at. % Cr, deposited using low (−200 V) and high (−1000 V) specimen bias during processing are composed of nanocrystalline metallic Cr and face-centered cubic chromium carbide, respectively surrounded by an amorphous matrix. The Cr-DLC film deposited at high bias exhibited enhanced adhesion to Si substrate and wear resistance compared to those deposited at low bias with the same Cr content. Wear rate of the films deposited at high bias is relatively independent of Cr content up to about 10 at. % (of the order of 10−7 mm3/N-m) and then increases with increasing Cr content. The coefficient of friction for the films with a Cr content less than 19 at. % is low and remains between 0.1-0.16.

scholarly journals Development of Ternary and Quaternary Catalysts for the Electrooxidation of Glycerol

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
L. M. Artem ◽  
D. M. Santos ◽  
A. R. De Andrade ◽  
K. B. Kokoh ◽  
J. Ribeiro
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cyclic Voltammetry ◽  
Pechini Method ◽  
Particle Sizes ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Face Centered

This work consisted in the preparation of platinum-based catalysts supported on carbon (Vulcan XC-72) and investigation of their physicochemical and electrochemical properties. Catalysts of the C/Pt-Ni-Sn-Me (Me = Ru or Ir) type were prepared by the Pechini method at temperature of350∘C. Four different compositions were homemade: C/Pt60Sn10Ni30, C/Pt60Sn10Ni20Ru10, C/Pt60Sn10Ni10Ru20, and C/Pt60Sn10Ni10Ir20. These catalysts were electrochemically and physically characterized by cyclic voltammetry (CV), chronoamperometry (CA) in the presence of glycerol 1.0 mol dm-3, X-ray diffraction (XRD), and high-resolution transmission electron microscopy (HRTEM). XRD results showed the main peaks of face-centered cubic Pt. The particle sizes obtained from XRD and HRTEM experiments were close to values ranging from 3 to 8.5 nm. The CV results indicate behavior typical of Pt-based catalysts in acid medium. The CV and CA data reveal that quaternary catalysts present the highest current density for the electrooxidation of glycerol.

scholarly journals Raman Spectroscopy and Electrochemical Investigations of Pt Electrocatalyst Supported on Carbon Prepared through Plasma Pyrolysis of Natural Gas

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Tereza Cristina Santos Evangelista ◽  
Giordano Toscano Paganoto ◽  
Marco Cesar Cunegundes Guimarães ◽  
Josimar Ribeiro
Keyword(s):  
Cyclic Voltammetry ◽  
Natural Gas ◽  
Particle Sizes ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Plasma Pyrolysis ◽  
Face Centered ◽  
Electrochemical Characterisations ◽  
Vulcan Carbon

Physicochemical and electrochemical characterisations of Pt-based electrocatalysts supported on carbon (Vulcan carbon, C1, and carbon produced by plasma pyrolysis of natural gas, C2) toward ethanol electrooxidation were investigated. The Pt20/C180and Pt20/C280electrocatalysts were prepared by thermal decomposition of polymeric precursors at 350°C. The electrochemical and physicochemical characterisations of the electrocatalysts were performed by means of X-ray diffraction (XRD), transmission electron microscope (TEM), Raman scattering, cyclic voltammetry, and chronoamperometry tests. The XRD results show that the Pt-based electrocatalysts present platinum metallic which is face-centered cubic structure. The results indicate that the Pt20/C180electrocatalyst has a smaller particle size (10.1–6.9 nm) compared with the Pt20/C280electrocatalyst; however, the Pt20/C280particle sizes are similar (12.8–10.4 nm) and almost independent of the reflection planes, which suggests that the Pt crystallites grow with a radial shape. Raman results reveal that both Vulcan carbon and plasma carbon are graphite-like materials consisting mostly of sp2carbon. Cyclic voltammetry and chronoamperometry data obtained in this study indicate that the deposition of Pt on plasma carbon increases its electrocatalytic activity toward ethanol oxidation reaction.

Synthesis and Magnetic Properties of FePt /Silica Core-Shell Nanoparticles

2010 ◽  
Vol 178 ◽  
pp. 291-295 ◽  
Author(s):  
Cui Xia Li ◽  
Zhi Hong Li ◽  
Xue Yan Du ◽  
Hai Xia Guo
Keyword(s):  
Magnetic Properties ◽  
Reverse Micelles ◽  
Core Shell ◽  
Fept Nanoparticles ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Shell Nanoparticles ◽  
Transmission Electron ◽  
Face Centered ◽  
Core Shell Nanoparticles

FePt nanoparticles (NPS), ~2nm in diameter, were synthesized and then coated with silica (SiO2) shells ~1.5nm-thick using reverse micelles as nanoreactors. The silica-coated FePt core–shell (FePt @silica) NPS were characterized by direct techniques of transmission electron microscopy (TEM). The results showed that the silica shells prevented the aggregation in liquid comparing to their bare counterparts. The as-synthesized FePt@SiO2 NPS exhibited essential characteristics of superparamagnetic behavior, as investigated by a vibrating sample magnetometer (VSM). X-ray diffraction (XRD) studies proved that the annealing at 700 °C for 30min under argon atmosphere caused the crystal structure of FePt core to transform from disordered face centered cubic (fcc) to the chemically ordered L10 FePt with face-centered tetragonal (fct) structure. This phase transition caused the change of magnetic properties of the FePt@SiO2 particles from superparamagnetism to ferromagnetism.

Synthesis and Characterization of Nanocrystalline CeO2

2006 ◽  
Vol 306-308 ◽  
pp. 1103-1108
Author(s):  
Abdul Hadi ◽  
Iskandar Idris Yaacob
Keyword(s):  
Fine Particles ◽  
Gas Adsorption ◽  
Mesoporous Structure ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Face Centered ◽  
Adsorption Desorption

Nanocrystalline CeO2 has been synthesized at room temperature using water-in-oil (w/o) microemulsion technique. The structure and properties of the nanocrystalline CeO2 were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and gas adsorption desorption measurement. XRD results showed the synthesized CeO2 has a face centered cubic structure with crystallite size of about 5.2 nm. TEM observation also indicated the presence of nanometer sized particles of CeO2. Coarser particles were also observed due to agglomeration. Gas adsorption desorption isotherms showed the behavior of fine particles with mesoporous structure.

scholarly journals Electrochemical and Morphological Investigations of Ga Addition to Pt Electrocatalyst Supported on Carbon

2017 ◽  
Vol 2017 ◽  
pp. 1-15 ◽  
Author(s):  
Giordano T. Paganoto ◽  
Deise M. Santos ◽  
Tereza C. S. Evangelista ◽  
Marco C. C. Guimarães ◽  
Maria Tereza W. D. Carneiro ◽  
...  
Keyword(s):  
Electrochemical Impedance ◽  
Physicochemical Characterization ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Precursor Method ◽  
Tem Analysis ◽  
X Ray ◽  
Transmission Electron ◽  
Face Centered

This paper is consisted in the synthesis of platinum-based electrocatalysts supported on carbon (Vulcan XC-72) and investigation of the addition of gallium in their physicochemical and electrochemical properties toward ethanol oxidation reaction (EOR). PtGa/C electrocatalysts were prepared through thermal decomposition of polymeric precursor method at a temperature of 350°C. Six different compositions were homemade: Pt50Ga50/C, Pt60Ga40/C, Pt70Ga30/C, Pt80Ga20/C, Pt90Ga10/C, and Pt100/C. These electrocatalysts were electrochemically characterized by cyclic voltammetry (CV), chronoamperometry (CA), chronopotentiometry (CP), and electrochemical impedance spectroscopy (EIS) in the presence and absence of ethanol 1.0 mol L−1. Thermogravimetric analysis (TGA), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and transmission electron microscopy (TEM) were also carried out for a physicochemical characterization of those materials. XRD results showed the main peaks of face-centered cubic Pt. The particle sizes obtained from XRD and TEM analysis range from 7.2 nm to 12.9 nm. The CV results indicate behavior typical of Pt-based electrocatalysts in acid medium. The CV, EIS, and CA data reveal that the addition of up to 31% of gallium to the Pt highly improves catalytic activity on EOR response when compared to Pt100/C.

FORMATION OF NOVEL Cu3Au ALLOY PHASE UNDER CONFINEMENT

2005 ◽  
Vol 04 (05n06) ◽  
pp. 1011-1020
Author(s):  
SUBHENDU SARKAR ◽  
ALOKMAY DATTA ◽  
PURUSHOTTAM CHAKRABORTY
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Atomic Ratio ◽  
Float Glass ◽  
Alloy Formation ◽  
X Ray Diffraction ◽  
Oriented Growth ◽  
Cross Sectional ◽  
Multilayer Systems ◽  
Transmission Electron ◽  
Interfacial Confinement

Our present work deals with the formation and thermal behavior of a nonbulk alloy phase confined within about 8 nm across the interfaces of Au/Cu multilayer systems. These multilayers deposited on silicon and float glass by DC magnetron sputtering have been studied by secondary ion mass spectrometry (SIMS), X-ray diffraction (XRD) and cross-sectional transmission electron microscopy (XTEM). Along with the highly oriented growth of the Cu and Au layers along [111], Cu 3 Au alloy was found to be present only at the Cu/Au interfaces in the nonbulk tetragonal D023 phase. Co -sputtering of Au and Cu under similar conditions produces only conventional fcc Cu 3 Au alloy phases, suggesting that interfacial confinement plays a significant role in producing the novel Cu 3 Au alloy phase in gold/copper multilayers. This novel phase is found to form only when the interfacial width is less than 10 nm. The D023 alloy phase tends to stabilize, rather than transforming to the bulk L12 phase, when the multilayer is vacuum-annealed at 150°C. As alloy formation spreads out of the interfaces (on vacuum annealing at 200°C), the dominant alloy is CuAu , consistent with the Cu:Au atomic ratio averaged over the multilayer.

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