High-Resolution-Electron-Microscopy Investigation of Nanosize Inclusions

MRS Bulletin ◽  
1997 ◽  
Vol 22 (8) ◽  
pp. 49-52 ◽  
Author(s):  
U. Dahmen ◽  
E. Johnson ◽  
S.Q. Xiao ◽  
A. Johansen
Keyword(s):  
Electron Microscopy ◽  
Melting Point ◽  
Giant Magnetoresistance ◽  
Materials Science ◽  
Semiconductor Nanocrystals ◽  
High Resolution Electron Microscopy ◽  
Solid Particles ◽  
Atomic Scale ◽  
Size And Shape ◽  
New Frontier

The behavior of solids in the nanometer size regime, as their dimensions approach the atomic scale, is of increasing fundamental and applied interest in materials research. Electronic, optical, magnetic, mechanical, or thermodynamic properties all may depend on the size and shape of the solid. As a result, in the nanoscale regime, size and shape may be used as design variables to tailor a material's properties such as giant magnetoresistance in multilayer films, or the optical properties in semiconductor nanocrystals. In most cases, the size dependence of properties is not well-understood. Nanophase materials constitute a new frontier in materials science, and accurate nanoscale characterization is extremely important in exploring this new frontier. In this area, transmission electron microscopy (TEM) plays a key role. Because of its unique ability to provide information on the structure and composition of internal interfaces in solids, TEM is particularly important in cases of buried nanophase structures such as small solid inclusions—that is, solid particles embedded within another solid.Nanoscale inclusions have recently been shown to exhibit unusual melting behavior that depends strongly on their size and the embedding matrix. For example, small inclusions of Pb in SiO exhibit melting-point depressions of several hundred degrees, whereas similarsized Pb inclusions in aluminum have shown large increases in melting point. Although a full understanding of these effects is still lacking, it appears that they are related not just to inclusion size but also to their shape and interface structure.

Atomic-Scale Measurement of Structure and Chemistry of a Single-Unit-Cell Layer of LaAlO3 Embedded in SrTiO3

2013 ◽  
Vol 19 (2) ◽  
pp. 310-318 ◽  
Author(s):  
Chun-Lin Jia ◽  
Juri Barthel ◽  
Felix Gunkel ◽  
Regina Dittmann ◽  
Susanne Hoffmann-Eifert ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Materials Science ◽  
Single Layer ◽  
High Resolution Electron Microscopy ◽  
Unit Cell ◽  
Atomic Scale ◽  
Chemical Information ◽  
Nominal Thickness ◽  
Specimen Area

AbstractA single layer of LaAlO3 with a nominal thickness of one unit cell, which is sandwiched between a SrTiO3 substrate and a SrTiO3 capping layer, is quantitatively investigated by high-resolution transmission electron microscopy. By the use of an aberration-corrected electron microscope and by employing sophisticated numerical image simulation procedures, significant progress is made in two aspects. First, the structural as well as the chemical features of the interface are determined simultaneously on an atomic scale from the same specimen area. Second, the evaluation of the structural and chemical data is carried out in a fully quantitative way on the basis of the absolute image contrast, which has not been achieved so far in materials science investigations using high-resolution electron microscopy. Considering the strong influence of even subtle structural details on the electronic properties of interfaces in oxide materials, a fully quantitative interface analysis, which makes positional data available with picometer precision together with the related chemical information, can contribute to a better understanding of the functionality of such interfaces.

The Role of Atomic Scale Investigation in the Development of Nanoscale Materials for Information Storage Applications

2004 ◽  
Vol 10 (3) ◽  
pp. 366-372 ◽  
Author(s):  
A.K. Petford-Long ◽  
D.J. Larson ◽  
A. Cerezo ◽  
X. Portier ◽  
P. Shang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Giant Magnetoresistance ◽  
High Resolution Electron Microscopy ◽  
Atom Probe ◽  
Information Storage ◽  
Atomic Scale ◽  
Chemical Mapping ◽  
Microstructural Parameters ◽  
Sufficient Detail ◽  
Resolution Electron

It is well established that the response of devices based on the giant magnetoresistance (GMR) effect depends critically on film microstructure, with parameters such as interfacial abruptness, the roughness and waviness of the layers, and grain size being crucial. Such devices have applications in information storage systems, and are therefore of great technological interest as well as being of fundamental scientific interest. The layers must be studied at high spatial resolution if the microstructural parameters are to be characterized with sufficient detail to enable the effects of fabrication conditions on properties to be understood, and the techniques of high resolution electron microscopy, transmission electron microscopy chemical mapping, and atom probe microanalysis are ideally suited. This article describes the application of these techniques to a range of materials including spin valves, spin tunnel junctions, and GMR multilayers.

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.

X-Ray-Optical Multilayer Structures Studied Using High Resolution Electron Microscopy.

1986 ◽  
Vol 77 ◽  
Author(s):  
Mary Beth Stearns ◽  
Amanda K. Petford-Long ◽  
C.-H. Chang ◽  
D. G. Stearns ◽  
N. M. Ceglio ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Substrate Surface ◽  
High Resolution Electron Microscopy ◽  
Atomic Scale ◽  
Degree Of Crystallinity ◽  
Multilayer Systems ◽  
Layer Width ◽  
X Ray ◽  
Resolution Electron

ABSTRACTThe technique of high resolution electron microscopy has been used to examine the structure of several multilayer systems (MLS) on an atomic scale. Mo/Si multilayers, in use in a number of x-ray optical element applications, and Mo/Si multilayers, of interest because of their magnetic properties, have been imaged in cross-section. Layer thicknesses, flatness and smoothness have been analysed: the layer width can vary by up to 0.6nm from the average value, and the layer flatness depends on the quality of the substrate surface for amorphous MLS, and on the details of the crystalline growth for the crystalline materials. The degree of crystallinity and the crystal orientation within the layers have also been investigated. In both cases, the high-Z layers are predominantly crystalline and the Si layers appear amorphous. Amorphous interfacial regions are visible between the Mo and Si layers, and crystalline cobalt suicide interfacial regions between the Co and Si layers. Using the structural measurements obtained from the HREM results, theoretical x-ray reflectivity behaviour has been calculated. It fits the experimental data very well.

Atomic Scale Study of Cosi/Si (111) and CoSi2/Si (111) Interfaces

1989 ◽  
Vol 159 ◽  
Author(s):  
A. Catana ◽  
M. Heintze ◽  
P.E. Schmid ◽  
P. Stadelmann
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
High Resolution ◽  
Orientation Relationship ◽  
Cross Sections ◽  
High Resolution Electron Microscopy ◽  
Atomic Scale ◽  
Type B ◽  
Initial Stage ◽  
Resolution Electron

ABSTRACTHigh Resolution Electron Microscopy (HREM) was used to study microstructural changes related to the CoSi/Si-CoSi/CoSi2/Si-CoSi2/Si transformations. CoSi is found to grow epitaxially on Si with [111]Si // [111]CoSi and < 110 >Si // < 112 >CoSi. Two CoSi non-equivalent orientations (rotated by 180° around the substrate normal) can occur in this plane. They can be clearly distinguished by HRTEM on cross-sections ( electron beam along [110]Si). At about 500°C CoSi transforms to CoSi2. Experimental results show that the type B orientation relationship satisfying [110]Si // [112]CoSi is preserved after the initial stage of CoSi2 formation. At this stage an epitaxial CoSi/CoSi2/Si(111) system is obtained. The atomic scale investigation of the CoSi2/Si interface shows that a 7-fold coordination of the cobalt atoms is observed in both type A and type B epitaxies.

Interfacial Atomic Structures During Cobalt Silicidation

1990 ◽  
Vol 202 ◽  
Author(s):  
A. Catana ◽  
P.E. Schmid
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Atomic Scale ◽  
Type B ◽  
Cross Sectional ◽  
Atomic Structures ◽  
Resolution Electron ◽  
Predominant Orientation ◽  
Lower Temperature

ABSTRACTHigh Resolution Electron Microscopy (HREM) and image calculations are combined to study microstructural changes related to the CoSi/Si-CoSi/CoSi2/Si-CoSi2/Si transformations. The samples are prepared by UHV e-beam evaporation of Co layers (2 nm) followed by annealing at 300°C or 400°C. Cross-sectional observations at an atomic scale show that the silicidation of Co at the lower temperature yields epitaxial CoSi/Si domains such that [111]Si // [111]CoSi and <110>Si // <112>CoSi. At about 400°C CoSi2 nucleates at the CoSi/Si interface. During the early stages of this chemical reaction, an epitaxial CoSi/CoSi2/Si system is observed. The predominant orientation is such that (021) CoSi planes are parallel to (220) CoSi2 planes, the CoSi2/Si interface being of type B. The growth of CoSi2 is shown to proceed at the expense of both CoSi and Si.

Trends in Atomic Resolution Electron Microscopy

1994 ◽  
Vol 332 ◽  
Author(s):  
David J. Smith ◽  
M.R. Mccartney
Keyword(s):  
Electron Microscopy ◽  
Structural Information ◽  
High Resolution Electron Microscopy ◽  
Operating Conditions ◽  
Atomic Scale ◽  
Irradiation Damage ◽  
Image Recording ◽  
Exit Surface ◽  
Resolution Electron ◽  
Image Simulations

ABSTRACTStructural information on the atomic scale is readily accessible from thin samples using the technique of high-resolution electron microscopy. Electron micrographs recorded under well-defined operating conditions can be directly interpreted in terms of atomic arrangements around defects of interest such as dislocations and interfaces. Digital image recording with slow-scan CCD cameras and quantitative comparisons with image simulations based on structural models are starting to lead to improved accuracy and reliability in structure determinations. Techniques based upon holographic methods are utilizing the superior illumination coherence of the field emission electron source to enhance resolution beyond the conventional extended Scherzer limit. Innovative methods for combining image and diffraction pattern information are also leading to improved levels of resolution for periodic objects. Care is needed to ensure that electron irradiation damage and surface cleanliness do not impose unnecessary restrictions on the details that can be extracted from recorded micrographs. It is proposed that the complex wavefunction emerging from the exit-surface of the sample should be considered as a basis for comparing the differences between experimental micrographs and image simulations.

High resolution electron microscopy of bismuth and thallium superconductors

1988 ◽  
Vol 46 ◽  
pp. 868-869
Author(s):  
J. P. Zhang ◽  
D. J. Li ◽  
H. Shibahara ◽  
L. D. Marks
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Shear Wave ◽  
High Resolution Electron Microscopy ◽  
Double Layers ◽  
Resolution Electron ◽  
New Frontier ◽  
Image Simulations

A new frontier has opened up in the field of superconductivity with the very recent discovery of compounds of bismuth and thallium which appear to superconduct above 100 K. Both of these compounds appear to be perovskite derivatives with intergrowth of the basic perovskite with bismuth double-layers and perhaps thallium double layers. The structure of these compounds, however, is not as yet completely established, particularly the thallium material which to date has only been produced in very small quantities due to the toxic nature of thallium.We have very recently been studying both the bismuth and thallium superconductors by high resolution electron microscopy. The bismuth material appears to be an intergrowth of a five layer perovskite with a buckling of the structure along the b axis (see Figure 1) which preliminary image simulations suggest is in the form of a shear wave of amplitude in the region of 0.25 Angstroms.

Sign in / Sign up

Export Citation Format

Share Document