AP-FIM INVESTIGATION OF THE INITIAL STAGE OF OXIDATION ON THE SURFACE OF ALLOYS

1995 ◽  
Vol 02 (02) ◽  
pp. 177-181 ◽  
Author(s):  
D.G. REN
Keyword(s):  
Binding Energy ◽  
Field Strength ◽  
Metal Atom ◽  
Exposure Period ◽  
Atom Probe ◽  
Field Evaporation ◽  
Residual Oxygen ◽  
Metal Atoms ◽  
Initial Stage ◽  
The Difference

This paper reports a study of the initial stage of oxidation on the surface of alloys by field-ion microscopy and atom probe (AP-FIM). The samples used in this investigation contained Ni, Ni-Cr, Ni-Al, Ti-Al , and Pt-Rh metals and alloys. A clean-tip surface, after atom-probe analysis, was exposed in the atmosphere of residual oxygen (vacuum 10−4 torr) for a few hours. AP analysis found that a small quantity of oxygen was adsorbed on the surface of the alloys. The clusters of a combination of a metal atom with an oxygen, i.e., PtO +2, NiO +2, and TiO +2 were determined by AP. The experiment found that the binding energy between metal atom on the surface of alloys was reduced when oxygen was adsorbed on the surface. The binding energy of surface atoms was determined according to the field strength of the tip surface. The reduction of the binding energy was about 0.5–2.0 eV, which changed following the exposure period in the atmosphere and depending on the kind of alloys used. The difference in field-ion image due to adsorption of oxygen was observed as compared to without the oxygen. The results of the experiment show that oxygen was absorbed on the “clean surface” of alloys. First the oxygen molecule was dissociated to oxygen atoms by the reaction with metal atoms and then formed the metal-oxygen bonding (M+O→MO) . This is an initial stage of oxidation on the surface of alloys. The clusters of combining oxygen did not dissociate during the field-evaporation process with 4.5 V/Å field strength.

scholarly journals Enhanced Atom Probe Imaging using Generalised Field Evaporation Models

2021 ◽  
Vol 27 (S1) ◽  
pp. 404-406
Author(s):  
Charles Fletcher ◽  
Michael Moody ◽  
Jeroen Scheerder ◽  
Claudia Fleischmann ◽  
Brian Geiser ◽  
...  
Keyword(s):  
Atom Probe ◽  
Field Evaporation ◽  
Evaporation Models

Atom-probe study of the initial stage of selective oxidation of Ni from the Cu-Ni alloy system

1991 ◽  
Vol 245 (1-2) ◽  
pp. 132-149 ◽  
Author(s):  
K. Hono ◽  
T. Iwata ◽  
M. Nakamura ◽  
H.W. Pickering ◽  
I. Kamiya ◽  
...  
Keyword(s):  
Selective Oxidation ◽  
Alloy System ◽  
Atom Probe ◽  
Initial Stage ◽  
Ni Alloy

Second hyperpolarizability of multimetallocenes [Cp–Mn–Cp] of Be, Mg and Ca

2015 ◽  
Vol 14 (01) ◽  
pp. 1550002 ◽  
Author(s):  
Kaushik Hatua ◽  
Prasanta K. Nandi
Keyword(s):  
Charge Transfer ◽  
Theoretical Study ◽  
Small Variation ◽  
Cooperative Effect ◽  
Second Hyperpolarizability ◽  
Nlo Property ◽  
Metal Atoms ◽  
Bonding Interaction ◽  
Charge Transfer Transitions ◽  
The Difference

Multimetallocene complexes ( Cp – M n– Cp ) of Be , Mg and Ca have been considered for the theoretical study of static second hyperpolarizability using a number of DFT functionals. Owing to the cooperative effect in bonding, beryllium forms multiberyllocene complexes ( Cp – Be n– Cp ) which have sufficient thermal stability with respect to dissociation into neutral fragments up to n = 10. On the other hand, multimetallocene complexes of Mg and Ca are found to be stable for n ≤ 5 which may be due to the weaker covalent bonding interaction between the larger metal atoms. The rather small variation of linear and cubic polarizabilities of Cp – Be n– Cp complexes beyond n = 5 arises from the rather weaker charge transfer transitions. The difference in NLO property among the investigated metal complexes arises from the extent of charge transfer from the terminal metal atoms and the distance between them. The charge transfer at longer distances in the ground state of Mg and Ca complexes leads to more intense electronic transition — the spectroscopic parameters of which strongly favors the enhancement of second hyperpolarizability.

Understanding of Capping Effects on the Tip Shape Evolution and on the Atom Probe Data of Bulk LaAlO3 Using Transmission Electron Microscopy

2017 ◽  
Vol 23 (2) ◽  
pp. 329-335 ◽  
Author(s):  
Chang-Min Kwak ◽  
Young-Tae Kim ◽  
Chan-Gyung Park ◽  
Jae-Bok Seol
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Atom Probe ◽  
Resolving Power ◽  
Shape Evolution ◽  
Oxide Materials ◽  
Field Evaporation ◽  
Laser Illumination ◽  
Transmission Electron ◽  
Mass Resolving Power

AbstractTwo challenges exist in laser-assisted atom probe tomography (APT). First, a drastic decline in mass-resolving power is caused, not only by laser-induced thermal effects on the APT tips of bulk oxide materials, but also the associated asymmetric evaporation behavior; second, the field evaporation mechanisms of bulk oxide tips under laser illumination are still unclear due to the complex relations between laser pulse and oxide materials. In this study, both phenomena were investigated by depositing Ni- and Co-capping layers onto the bulk LaAlO3 tips, and using stepwise APT analysis with transmission electron microscopy (TEM) observation of the tip shapes. By employing the metallic capping, the heating at the surface of the oxide tips during APT analysis became more symmetrical, thereby enabling a high mass-resolving power in the mass spectrum. In addition, the stepwise microscopy technique visualized tip shape evolution during APT analysis, thereby accounting for evaporation sequences at the tip surface. The combination of “capping” and “stepwise APT with TEM,” is applicable to any nonconductors; it provides a direct observation of tip shape evolution, allows determination of the field evaporation strength of oxides, and facilitates understanding of the effects of ultrafast laser illumination on an oxide tip.

Effect of Additional Irradiation at Different Fluxes on RPV Embrittlement

2009 ◽  
Author(s):  
Kenji Dohi ◽  
Kenji Nishida ◽  
Akiyoshi Nomoto ◽  
Naoki Soneda ◽  
Hiroshi Matsuzawa ◽  
...  
Keyword(s):  
Neutron Flux ◽  
Solute Atom ◽  
Volume Fraction ◽  
Neutron Fluence ◽  
Three Dimensional ◽  
Atom Probe ◽  
Atom Clusters ◽  
Neutron Fluences ◽  
The Difference ◽  
Test Reactor

The effect of the neutron flux at high fluence on the microstructural and hardness changes of a reactor pressure vessel (RPV) steel was investigated. An accelerated test reactor irradiation of a RPV material, previously irradiated in commercial reactors, was carried out at the lowest possible neutron fluxes in order to obtain neutron fluences up to approximately 1×1020 n/cm2 (E>1MeV). State-of-the-art experimental techniques such as three-dimensional atom probe were applied to carry out advanced quantitative characterization of defect features in the materials. Results for the same material irradiated in both high and low flux conditions are compared. For neutron fluences above 6×1019 n/cm2 (E>1MeV) the difference in the neutron fluence dependence of the increase in hardness is not seen for any neutron flux condition. The volume fraction of solute atom clusters increases linearly with neutron fluence, and the influence of neutron flux is not significant. The component elements and the chemical composition of the solute atom clusters formed by the irradiation do not change regardless of the neutron fluence and flux. The square root of the volume fraction of the solute atom clusters is a good correlation with the increase in hardness.

Hexaruthenium and octaruthenium carbonyl cluster complexes derived from 2-amino-6-methylpyridine — Novel coordination modes for 2-imidopyridines

2006 ◽  
Vol 84 (2) ◽  
pp. 105-110 ◽  
Author(s):  
Javier A Cabeza ◽  
Ignacio del Río ◽  
Pablo García-Álvarez ◽  
Daniel Miguel
Keyword(s):  
Metal Atom ◽  
Cluster Compounds ◽  
Carbonyl Cluster ◽  
Amido Ligands ◽  
Ruthenium Cluster ◽  
Coordination Type ◽  
Metal Atoms ◽  
Pyridine Nitrogen ◽  
Cluster 2 ◽  
Reflux Temperature

The hexanuclear ruthenium cluster [Ru6(µ3-H)2(µ-H)2(µ4-κ2-ampy)2(CO)14] (1) and the octanuclear one [Ru8(µ-H)(µ4-κ2-ampy)3(µ3-κ2-Hampy)(µ-CO)2(CO)15] (2) have been prepared by treating [Ru6(µ3-H)2(µ5-κ2-ampy)(µ-CO)2(CO)14] with 2-amino-6-methylpyridine (H2ampy) in decane at reflux temperature. Their metal atoms are supported by ligands that derive from the activation of one (complex 2) or both N—H bonds (complexes 1 and 2) of the H2ampy amino fragment. Both contain at least one ampy ligand featuring an unprecedented coordination type: the imido N atom caps a triangle of metal atoms while the pyridine nitrogen is attached to an additional metal atom. One of the ampy ligands of cluster 2 also displays another unprecedented coordination type: it caps a distorted square of metal atoms through the imido N atom while the pyridine nitrogen is attached to one of the atoms included in that square.Key words: ruthenium, cluster compounds, amido ligands, imido ligands.

scholarly journals Study of the field evaporation mechanism of laser-assisted atom probe

2011 ◽  
Vol 17 (3) ◽  
pp. 224-226 ◽  
Author(s):  
Tetsuo Terakawa ◽  
Norihito Mayama ◽  
Yasuko Kajiwara ◽  
Masanori Owari
Keyword(s):  
Atom Probe ◽  
Field Evaporation ◽  
Evaporation Mechanism

scholarly journals Automated Atom-By-Atom Three-Dimensional (3D) Reconstruction of Field Ion Microscopy Data

2017 ◽  
Vol 23 (2) ◽  
pp. 255-268 ◽  
Author(s):  
Michal Dagan ◽  
Baptiste Gault ◽  
George D. W. Smith ◽  
Paul A. J. Bagot ◽  
Michael P. Moody
Keyword(s):  
Three Dimensional ◽  
Reconstruction Algorithm ◽  
Automated Analysis ◽  
Atom Probe ◽  
Crystal Defects ◽  
Steel Matrix ◽  
Field Evaporation ◽  
Field Ion Microscopy ◽  
Ion Microscopy ◽  
Microscopy Data

AbstractAn automated procedure has been developed for the reconstruction of field ion microscopy (FIM) data that maintains its atomistic nature. FIM characterizes individual atoms on the specimen’s surface, evolving subject to field evaporation, in a series of two-dimensional (2D) images. Its unique spatial resolution enables direct imaging of crystal defects as small as single vacancies. To fully exploit FIM’s potential, automated analysis tools are required. The reconstruction algorithm developed here relies on minimal assumptions and is sensitive to atomic coordinates of all imaged atoms. It tracks the atoms across a sequence of images, allocating each to its respective crystallographic plane. The result is a highly accurate 3D lattice-resolved reconstruction. The procedure is applied to over 2000 tungsten atoms, including ion-implanted planes. The approach is further adapted to analyze carbides in a steel matrix, demonstrating its applicability to a range of materials. A vast amount of information is collected during the experiment that can underpin advanced analyses such as automated detection of “out of sequence” events, subangstrom surface displacements and defects effects on neighboring atoms. These analyses have the potential to reveal new insights into the field evaporation process and contribute to improving accuracy and scope of 3D FIM and atom probe characterization.

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