Characterization and modeling of nanotips fabricated in the field ion microscope

2016 ◽  
Vol 5 (3) ◽  
Author(s):  
Ahmed Ali ◽  
Hassan Barada ◽  
Moh’d Rezeq
Keyword(s):  
Electron Bombardment ◽  
Scanning Probe ◽  
Single Atom ◽  
Local Electron ◽  
Characterization Methods ◽  
Simulation Tools ◽  
Element Simulation ◽  
Electron Microscopes ◽  
Field Ion Microscope

AbstractNanotips are considered significant elements in some of nanotechnology instruments. They are used in scanning probe microscopes and electron microscopes to characterize materials at the nano and atomic scales. Therefore, the size and profile of the nanotip determines the performance of these microscopes. The advancement of nanotip fabrication techniques has enabled the fabrication of ultra-sharp tips and even single-atom tips. However, the characterization of nanotips with an apex of a few nanometers is still premature, while the conventional characterization methods of the tip size, such as the ring counting method, have shown some limitation at this nano scale. In this paper, we review the various nanotip fabrication methods with a focus on the most recent one, which is called the local electron bombardment method. We demonstrate an approach for estimating the nanotip radius with good approximation using ball crystal models. We also model the overall nanotip profile using finite element simulation tools based on the hyperboloidal geometry. The modeling and radius estimation approach is applied on tips fabricated by the local electron bombardment method, which will be explained in detail as well.

Atomic Spectroscopy in the FIM

1986 ◽  
Vol 44 ◽  
pp. 758-761
Author(s):  
J. J. Hren ◽  
S. D. Walck
Keyword(s):  
Electron Microscope ◽  
Electric Fields ◽  
Atom Probe ◽  
Atomic Spectroscopy ◽  
Single Atom ◽  
Statistical Sampling ◽  
Commercial Instrument ◽  
Available Technology ◽  
High Electric Fields ◽  
Field Ion Microscope

The field ion microscope (FIM) has had the ability to routinely image the surface atoms of metals since Mueller perfected it in 1956. Since 1967, the TOF Atom Probe has had single atom sensitivity in conjunction with the FIM. “Why then hasn't the FIM enjoyed the success of the electron microscope?” The answer is closely related to the evolution of FIM/Atom Probe techniques and the available technology. This paper will review this evolution from Mueller's early discoveries, to the development of a viable commercial instrument. It will touch upon some important contributions of individuals and groups, but will not attempt to be all inclusive. Variations in instrumentation that define the class of problems for which the FIM/AP is uniquely suited and those for which it is not will be described. The influence of high electric fields inherent to the technique on the specimens studied will also be discussed. The specimen geometry as it relates to preparation, statistical sampling and compatibility with the TEM will be examined.

Field ion microscope investigations of atomic processes at surfaces

1989 ◽  
Vol 47 ◽  
pp. 228-229
Author(s):  
G. L. Kellogg ◽  
P. R. Schwoebel
Keyword(s):  
Single Crystal ◽  
Crystal Surface ◽  
Linear Chain ◽  
Atom Probe ◽  
Nucleation And Growth ◽  
Single Atom ◽  
Initial Structure ◽  
Atomic Processes ◽  
Single Crystal Surfaces ◽  
Field Ion Microscope

Although no longer unique in its ability to resolve individual single atoms on surfaces, the field ion microscope remains a powerful tool for the quantitative characterization of atomic processes on single-crystal surfaces. Investigations of single-atom surface diffusion, adatom-adatom interactions, surface reconstructions, cluster nucleation and growth, and a variety of surface chemical reactions have provided new insights to the atomic nature of surfaces. Moreover, the ability to determine the chemical identity of selected atoms seen in the field ion microscope image by atom-probe mass spectroscopy has increased or even changed our understanding of solid-state-reaction processes such as ordering, clustering, precipitation and segregation in alloys. This presentation focuses on the operational principles of the field-ion microscope and atom-probe mass spectrometer and some very recent applications of the field ion microscope to the nucleation and growth of metal clusters on metal surfaces.The structure assumed by clusters of atoms on a single-crystal surface yields fundamental information on the adatom-adatom interactions important in crystal growth. It was discovered in previous investigations with the field ion microscope that, contrary to intuition, the initial structure of clusters of Pt, Pd, Ir and Ni atoms on W(110) is a linear chain oriented in the <111> direction of the substrate.

Preparation and Characterization of Single-Atom Tips

Nano Letters ◽  
2004 ◽  
Vol 4 (12) ◽  
pp. 2379-2382 ◽  
Author(s):  
Hong-Shi Kuo ◽  
Ing-Shouh Hwang ◽  
Tsu-Yi Fu ◽  
Jun-Yi Wu ◽  
Che-Cheng Chang ◽  
...  
Keyword(s):  
Single Atom

Measurement of Plasticity Gradients with Scanning Probe Microscopy

1993 ◽  
Vol 318 ◽  
Author(s):  
James D. Kiely ◽  
Dawn A. Bonnell
Keyword(s):  
Fracture Surface ◽  
Scanning Probe Microscopy ◽  
Scanning Probe ◽  
Scanning Tunneling ◽  
Ceramic System ◽  
Force Microscopy ◽  
Metal Fracture ◽  
Atomic Force ◽  
Metal Ceramic

ABSTRACTScanning Tunneling and Atomic Force Microscopy were used to characterize the topography of fractured Au /sapphire interfaces. Variance analysis which quantifies surface morphology was developed and applied to the characterization of the metal fracture surface of the metal/ceramic system. Fracture surface features related to plasticity were quantified and correlated to the fracture energy and energy release rate.

scholarly journals Emerging techniques in the isolation and characterization of extracellular vesicles and their roles in cancer diagnostics and prognostics

The Analyst ◽  
2016 ◽  
Vol 141 (2) ◽  
pp. 371-381 ◽  
Author(s):  
Vijaya Sunkara ◽  
Hyun-Kyung Woo ◽  
Yoon-Kyoung Cho
Keyword(s):  
Extracellular Vesicles ◽  
Cancer Diagnostics ◽  
Clinical Implementation ◽  
Characterization Methods ◽  
Cancer Management ◽  
Isolation And Characterization

We present an overview of current isolation, detection, and characterization methods of extracellular vesicles and their applications and limitations as a potential emerging biomarker in cancer management and their clinical implementation.

Incompressibility and mesh sensitivity analysis in finite element simulation of rubbers

2016 ◽  
Vol 7 (1) ◽  
pp. 7-12 ◽  
Author(s):  
D. Huri
Keyword(s):  
Finite Element ◽  
Material Characterization ◽  
Numerical Stability ◽  
Material Parameters ◽  
Linear Finite Element ◽  
Element Simulation ◽  
Finite Element Calculations ◽  
Mesh Density ◽  
Rubber Component

Non-linear finite element calculations are indispensable when important information of the material response under load of a rubber component is desired. Although the material characterization of a rubber component is a demanding engineering task, the changing contact range between the parts and the incompressibility behaviour of the rubber further increase the complexity of the investigations. In this paper the effects of the choice of the numerical material parameters (e.g. bulk modulus) are examined with regard to numerical stability, mesh density and calculation accuracy. As an example, a rubber spring is chosen where contact problem is also handled.

Unified Rotational and Translational Stiffness Characterization of Compliant Shell Mechanisms

2018 ◽  
Author(s):  
Joost R. Leemans ◽  
Charles J. Kim ◽  
Werner W. P. J. van de Sande ◽  
Just L. Herder
Keyword(s):  
Degrees Of Freedom ◽  
Compliant Mechanisms ◽  
Screw Theory ◽  
Characterization Methods ◽  
Six Degrees Of Freedom ◽  
Thin Walled Structures ◽  
Spatial Mechanisms ◽  
Eigen Decomposition ◽  
Comprehensive Characterization

Compliant shell mechanisms utilize spatially curved thin-walled structures to transfer or transmit force, motion or energy through elastic deformation. To design with spatial mechanisms designers need comprehensive characterization methods, while existing methods fall short of meaningful comparisons between rotational and translational degrees of freedom. This paper presents two approaches, both of which are based on the principle of virtual loads and potential energy, utilizing properties of screw theory, Plücker coordinates and an eigen-decomposition, leading to two unification lengths that can be used to compare and visualize all six degrees of freedom directions and magnitudes of compliant mechanisms in a non-arbitrary physically meaningful manner.

scholarly journals The memory effect of nanoscale memristors investigated by conducting scanning probe microscopy methods

2012 ◽  
Vol 3 ◽  
pp. 722-730 ◽  
Author(s):  
César Moreno ◽  
Carmen Munuera ◽  
Xavier Obradors ◽  
Carmen Ocal
Keyword(s):  
Memory Effect ◽  
Scanning Probe Microscopy ◽  
Electrical Characterization ◽  
Scanning Force Microscopy ◽  
Scanning Probe ◽  
Force Microscopy ◽  
Versatile Tool ◽  
Scanning Force ◽  
Memristor Device

We report on the use of scanning force microscopy as a versatile tool for the electrical characterization of nanoscale memristors fabricated on ultrathin La0.7Sr0.3MnO3 (LSMO) films. Combining conventional conductive imaging and nanoscale lithography, reversible switching between low-resistive (ON) and high-resistive (OFF) states was locally achieved by applying voltages within the range of a few volts. Retention times of several months were tested for both ON and OFF states. Spectroscopy modes were used to investigate the I–V characteristics of the different resistive states. This permitted the correlation of device rectification (reset) with the voltage employed to induce each particular state. Analytical simulations by using a nonlinear dopant drift within a memristor device explain the experimental I–V bipolar cycles.

scholarly journals Atomic Level Characterization of the Morphology of Phases in Chromindur Magnetic Alloys

1991 ◽  
Vol 232 ◽  
Author(s):  
M. K Miller ◽  
P. P. Camus ◽  
M. G. Hetherington
Keyword(s):  
Atom Probe ◽  
Heat Treatments ◽  
Miscibility Gap ◽  
Probe Field ◽  
Magnet Alloy ◽  
Two Phases ◽  
Isothermal Heat Treatments ◽  
Field Ion Microscope ◽  
Permanent Magnet Alloy

ABSTRACTThe atom probe field ion microscope has been used to characterize the morphology and determine the compositions of the iron-rich a and chromium-enriched α′ phases produced during isothermal and step cooled heat treatments in a Chromindur II ductile permanent magnet alloy. The good magnetic properties of this material are due to a combination of the composition of the two phases and the isolated nature and size of the ferromagnetic a phase. The morphology of the a phase is produced as a result of the shape of the miscibility gap and the step-cooled heat treatment and is distinctly different from that formed during isothermal heat treatments.

scholarly journals Viscoelastic characterization of an EPDM rubber and finite element simulation of its dry rolling friction

2008 ◽  
Vol 2 (3) ◽  
pp. 157-164 ◽  
Author(s):  
D. Felhos ◽  
D. Xu ◽  
A. K. Schlarb ◽  
K. Varadi ◽  
T. Goda
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Rolling Friction ◽  
Epdm Rubber ◽  
Element Simulation
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