scholarly journals Atom Probes Leap Ahead

2003 ◽  
Vol 11 (5) ◽  
pp. 8-13 ◽  
Author(s):  
Thomas F. Kelly ◽  
Amy A. Gribb
Keyword(s):  
Atomic Scale ◽  
Atom Probes ◽  
Electron Microscopes ◽  
Human Inquiry

Since early times, the collective understanding of our microscopic universe has been directly tied to the quality of our microscopies. This has been true from the advent of light microscopes through to modern electron microscopes. Indeed, if one is to work on a given scale, one must be able to “see” at that scale. At the beginning of the 21st century, human inquiry is focused on the atomic scale.

Atom probes as analytical microscopes

1995 ◽  
Vol 53 ◽  
pp. 290-291
Author(s):  
T. F. Kelly ◽  
P. P. Camus ◽  
D. J. Larson ◽  
S. S. Bajikar ◽  
L. M. Holzman
Keyword(s):  
Spatial Scales ◽  
Atom Probe ◽  
Atomic Scale ◽  
Three Dimensions ◽  
Single Atom ◽  
Probe Field ◽  
Atom Probes ◽  
Analytical Electron ◽  
Compositional Information ◽  
Electron Microscopes

Analytical microscopes are used to provide compositional and image information at spatial scales from the atomic (nm) to the macroscopic (mm). There are limitations in these techniques, however, and three in particular are noteworthy. 1) Compositional information at the atomic scale is not readily available. 2) The precision of the data is not high (limited to about a few part per thousand). 3) It is difficult or impossible to determine information about the composition in three dimensions.Atom probe field ion microscopy (APFIM) has historically been able to complement analytical electron microscopes (AEM) at the atomic scale but has not competed with them otherwise. For example, atomic-scale compositional information is inherent to APFIM but it has been difficult to extend this to large dimensions. Furthermore, APFIMs achieve single atom sensitivity which is difficult for AEMs in all but limited situations. In this paper, we consider how atom probes are evolving with capabilities which allow them to not only overcome some of the shortcomings of AEM, but also to compete directly with AEM against its strengths.

Limits for high-resolution electron microscopy of inorganic materials?

1987 ◽  
Vol 45 ◽  
pp. 4-5
Author(s):  
David J. Smith
Keyword(s):  
Electron Microscopy ◽  
Spherical Aberration ◽  
High Resolution Electron Microscopy ◽  
Inorganic Materials ◽  
Atomic Scale ◽  
Resolution Limit ◽  
Contrast Transfer Function ◽  
Existing Problems ◽  
Resolution Electron ◽  
Electron Microscopes

The era of atomic-resolution electron microscopy has finally arrived. In virtually all inorganic materials, including oxides, metals, semiconductors and ceramics, it is possible to image individual atomic columns in low-index zone-axis projections. A whole host of important materials’ problems involving defects and departures from nonstoichiometry on the atomic scale are waiting to be tackled by the new generation of intermediate voltage (300-400keV) electron microscopes. In this review, some existing problems and limitations associated with imaging inorganic materials are briefly discussed. The more immediate problems encountered with organic and biological materials are considered elsewhere.Microscope resolution. It is less than a decade since the state-of-the-art, commercially available TEM was a 200kV instrument with a spherical aberration coefficient of 1.2mm, and an interpretable resolution limit (ie. first zero crossover of the contrast transfer function) of 2.5A.

Methods to Monitor and Improve the Performance of Specimen Holders for Transmission Electron Cryomicroscopy

1996 ◽  
Vol 54 ◽  
pp. 454-455
Author(s):  
B. L. Armbruster ◽  
B. Kraus ◽  
M. Pan
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
Electron Beam Irradiation ◽  
Beam Irradiation ◽  
Quality Of Data ◽  
Electron Cryomicroscopy ◽  
Thermal Equilibration ◽  
Transmission Electron ◽  
Electron Microscopes

One goal in electron microscopy of biological specimens is to improve the quality of data to equal the resolution capabilities of modem transmission electron microscopes. Radiation damage and beam- induced movement caused by charging of the sample, low image contrast at high resolution, and sensitivity to external vibration and drift in side entry specimen holders limit the effective resolution one can achieve. Several methods have been developed to address these limitations: cryomethods are widely employed to preserve and stabilize specimens against some of the adverse effects of the vacuum and electron beam irradiation, spot-scan imaging reduces charging and associated beam-induced movement, and energy-filtered imaging removes the “fog” caused by inelastic scattering of electrons which is particularly pronounced in thick specimens.Although most cryoholders can easily achieve a 3.4Å resolution specification, information perpendicular to the goniometer axis may be degraded due to vibration. Absolute drift after mechanical and thermal equilibration as well as drift after movement of a holder may cause loss of resolution in any direction.

scholarly journals Dissimilar Metals Laser Welding between DP1000 Steel and Aluminum Alloy 1050

Metals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 102 ◽  
Author(s):  
António Pereira ◽  
Ana Cabrinha ◽  
Fábio Rocha ◽  
Pedro Marques ◽  
Fábio Fernandes ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Laser Welding ◽  
Mechanical Tests ◽  
Welding Parameters ◽  
Dissimilar Metals ◽  
Butt Welding ◽  
Electron Microscopes ◽  
1050 Aluminum Alloy ◽  
Scanning Electron Microscopes

The welding of dissimilar metals was carried out using a pulsed Nd: YAG laser to join DP1000 steel and an aluminum alloy 1050 H111. Two sheets of each metal, with 30 × 14 × 1 mm3, were lap welded, since butt welding proved to be nearly impossible due to the huge thermal conductivity differences and melting temperature differences of these materials. The aim of this research was to find the optimal laser welding parameters based on the mechanical and microstructure investigations. Thus, the welded samples were then subjected to tensile testing to evaluate the quality of the joining operation. The best set of welding parameters was replicated, and the welding joint obtained using these proper parameters was carefully analyzed using optical and scanning electron microscopes. Despite the predicted difficulties of welding two distinct metals, good quality welded joints were achieved. Additionally, some samples performed satisfactorily well in the mechanical tests, reaching tensile strengths close to the original 1050 aluminum alloy.

scholarly journals Shared Research Equipment at OAK Ridge National Laboratory

1998 ◽  
Vol 4 (S2) ◽  
pp. 470-471
Author(s):  
N. D. Evans ◽  
E. A. Kenik ◽  
M. K. Miller
Keyword(s):  
Semiconductor Device ◽  
National Laboratory ◽  
Atomic Scale ◽  
Fiscal Year ◽  
Probe Field ◽  
Oak Ridge ◽  
Wide Range ◽  
Oak Ridge National Laboratory ◽  
Electron Microscopes ◽  
Research Equipment

The Shared Research Equipment (SHaRE) User Facility and Program at Oak Ridge National Laboratory (ORNL) provides microanalytical facilities for studies within the materials sciences. Available instrumentation includes advanced analytical electron microscopes, atom probe field ion microscopes, and nanoindentation facilities. Through SHaRE, researchers from U.S. universities, industries, and government laboratories may collaborate with Facility scientists to perform research not possible at their home institutions. International collaborations are also possible. Most SHaRE projects seek correlations at the microscopic or atomic scale between structure and properties in a wide range of metallic, ceramic, and other structural materials. Typical research projects include studies of magnetic materials, advanced alloys, catalysts, semiconductor device materials, high Tc superconductors, and surface-modified polymers. Projects usually involve one or more external researchers visiting the SHaRE Facility for up to three weeks during the fiscal year (October 1 - September 30). Project approval is based upon the scientific excellence and relevance of proposed collaborative research.

Study of Nanocutting Using Atomic Model

2008 ◽  
Vol 33-37 ◽  
pp. 963-968
Author(s):  
Chun Yi Chu ◽  
Chung Ming Tan ◽  
Yung Chuan Chiou
Keyword(s):  
Molecular Dynamics ◽  
Energy Minimization ◽  
Atomic Scale ◽  
Scale Model ◽  
Atomistic Simulations ◽  
Cutting Depth ◽  
Cutting Deformation ◽  
Simulation Results ◽  
Model Approach

The stress induced in a workpiece under nanocutting are analyzed by an atomic-scale model approach that is based on the energy minimization. Certain aspects of the deformation evolution during the process of nanocutting are addressed. This method needs less computational efforts than traditional molecular dynamics (MD) calculations. The simulation results demonstrate that the microscopic cutting deformation mechanism in the nanocutting process can be regarded as the instability of the crystalline structure in our atomistic simulations and the surface quality of the finished workpiece varies with the cutting depth.

Magnetic properties of Exchange-spring DyFe2/YFe2 Superlattices by Monte Carlo Simulations

2012 ◽  
Vol 1471 ◽  
Author(s):  
Pierre-Emmanuel Berche ◽  
Saoussen Djedai ◽  
Etienne Talbot
Keyword(s):  
Monte Carlo ◽  
Magnetic Properties ◽  
Monte Carlo Simulations ◽  
Field Dependence ◽  
Hysteresis Loops ◽  
Atomic Scale ◽  
Exchange Spring ◽  
Scale Modelling ◽  
Different Temperatures

ABSTRACTMonte Carlo simulations are used to perform an atomic scale modelling of the magnetic properties of epitaxial exchange-coupled DyFe2/YFe2 superlattices. These samples, extremely well-researched experimentally, are constituted by a hard ferrimagnet DyFe2 and a soft ferrimagnet YFe2 antiferromagnetically coupled. Depending on the layers and on the temperature, the field dependence of the magnetization depth profile is complex. In this work, we reproduce by Monte Carlo simulations hysteresis loops for the net and compound-specific magnetizations at different temperatures, and assess the quality of the results by a direct comparison to experimental hysteresis loops.

Aberration-corrected HRTEM of the Incommensurate Misfit Layer Compound (PbS)1.14NbS2

2007 ◽  
Vol 1026 ◽  
Author(s):  
Magnus Garbrecht ◽  
Erdmann Spiecker ◽  
Wolfgang Jäger ◽  
Karsten Tillmann
Keyword(s):  
Spherical Aberration ◽  
Atomic Scale ◽  
Transition Metal Dichalcogenide ◽  
Layer Compound ◽  
X Ray ◽  
Medium Voltage ◽  
Transmission Electron ◽  
Interesting Class ◽  
Electron Microscopes ◽  
Set Up

AbstractThe development of tunable spherical aberration (Cs) imaging correctors for medium-voltage transmission electron microscopes (TEM) offers new opportunities for atomic-scale in-vestigations of materials. A very interesting class of microstructures regarding a variety of dif-ferent physical properties are the transition metal dichalcogenide misfit layer compounds exhibit-ing a high density of incommensurate interfaces due to their stacked nature. In the present study, the benefits coming along with the set-up of negative CS imaging (NCSI) conditions (in TEM) are demonstrated by means of different examples regarding local inhomogeneities in (PbS)1.14NbS2 crystals that can not be dissected in such detail by averaging x-ray techniques.

scholarly journals Atom Probe Tomography Defines Mainstream Microscopy at the Atomic Scale

2006 ◽  
Vol 14 (4) ◽  
pp. 34-41 ◽  
Author(s):  
Thomas F. Kelly ◽  
Keith Thompson ◽  
Emmanuelle A. Marquis ◽  
David J. Larson
Keyword(s):  
Atom Probe Tomography ◽  
Scanning Tunneling Microscope ◽  
Atom Probe ◽  
Atomic Scale ◽  
Process Equipment ◽  
Scanning Tunneling ◽  
Surface Scanning ◽  
Single Atoms ◽  
Transmission Electron ◽  
Electron Microscopes

When making a sculpture, it is the eyes that guide the hands and tools and perceive the outcome. In simple words, “in order to make, you must be able to see.” So too, when making a nanoelectronic device, it is the microscope (eyes) that guides the process equipment (hands and tools) and perceives the outcome. As we emerge into the century of nanotechnology, it is imperative that the eyes on the nanoworld provide an adequate ability to “see.” We have microscopies that resolve 0.02 nm on a surface (scanning tunneling microscope (STM)) or single atoms in a specimen (atom probe tomographs (APT) and transmission electron microscopes (TEM)).

Medical Technology Transfer in Major Chinese Medical Schools

1991 ◽  
Vol 7 (4) ◽  
pp. 553-560 ◽  
Author(s):  
Teh-wei Hu ◽  
Ying-ying Meng
Keyword(s):  
Technology Transfer ◽  
Economic Reform ◽  
High Performance ◽  
Medical Technology ◽  
Medical Schools ◽  
Laboratory Equipment ◽  
Republic Of China ◽  
Electron Microscopes ◽  
Domestic Products

AbstractThis paper examines how the decision-making process and its consequences affect medical technology transfer in major Chinese medical schools. Data are from a 1987 survey of 13 key medical universities, directly supervised by the Ministry of Public Health in the People's Republic of China. This paper limits itself to four types of laboratory equipment — electron microscopes, UV/VIS spectrophotometers, high-performance liquid chromatographs, and polygraphs. Decisions on the transfer of medical technology have been more decentralized in China since the economic reform in 1978. The major reason for schools to import these four types of equipment is their dissatisfaction with the quality of domestic products. Chinese medical schools depend heavily on the information provided at medical equipment exhibits and their neighboring schools. Their decisions to acquire the equipment are based more on the quality and service available than on the prices. Chinese medical schools face serious infrastructure problems in acquiring and maintaining these pieces of equipment. A number of suggestions are made for improving the efficiency of medical technology transfer in China.

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