Direct structure analysis of advanced nanomaterials by high-resolution electron microscopy

2012 ◽  
Vol 1 (5) ◽  
pp. 389-425 ◽  
Author(s):  
Takeo Oku
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Nanostructured Materials ◽  
Structure Analysis ◽  
Incident Beam ◽  
High Resolution Electron Microscopy ◽  
Structure Model ◽  
Resolution Electron ◽  
Correction Technique ◽  
Resolution Imaging

AbstractHigh-resolution electron microscopy (HREM) analysis has contributed to the direct structure analysis of advanced nanostructured materials, of which the properties of these materials are strongly dependent on the atomic arrangements. In the present article, the direct structure analysis of nanostructured materials such as boride and oxide materials was described and the high-resolution imaging methods were applied to boron nitride nanomaterials such as nanotubes and nanoparticles. An aberration correction technique is also expected as an advanced nanostructure analysis with higher resolution. The HREM image of TlBa2Ca3Cu4O11 was taken with the incident beam parallel to the a axis together with a structure model after image processing.

High-resolution electron microscopy of nanostructured materials

1995 ◽  
Vol 53 ◽  
pp. 172-173
Author(s):  
M. José-Yacamán
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Grain Boundaries ◽  
Nanostructured Materials ◽  
High Resolution Electron Microscopy ◽  
Hrem Image ◽  
Small Particles ◽  
Resolution Electron ◽  
Nanophase Materials

Electron microscopy is a fundamental tool in materials characterization. In the case of nanostructured materials we are looking for features with a size in the nanometer range. Therefore often the conventional TEM techniques are not enough for characterization of nanophases. High Resolution Electron Microscopy (HREM), is a key technique in order to characterize those materials with a resolution of ~ 1.7A. High resolution studies of metallic nanostructured materials has been also reported in the literature. It is concluded that boundaries in nanophase materials are similar in structure to the regular grain boundaries. That work therefore did not confirm the early hipothesis on the field that grain boundaries in nanostructured materials have a special behavior. We will show in this paper that by a combination of HREM image processing, and image calculations, it is possible to prove that small particles and coalesced grains have a significant surface roughness, as well as large internal strain.

Voltage-center COMA-free alignment for high-resolution Electron Microscopy

1994 ◽  
Vol 52 ◽  
pp. 410-411
Author(s):  
K. Ishizuka ◽  
K. Shirota
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Incident Beam ◽  
Chromatic Aberration ◽  
High Resolution Electron Microscopy ◽  
Beam Deflection ◽  
Objective Lens ◽  
Main Magnetic Field ◽  
Beam Direction ◽  
Resolution Electron

In a conventional alignment for high-resolution electron microscopy, the specimen point imaged at the viewing-screen center is made dispersion-free against a voltage fluctuation by adjusting the incident beam direction using the beam deflector. For high-resolution works the voltage-center alignment is important, since this alignment reduces the chromatic aberration. On the other hand, the coma-free alignment is also indispensable for high-resolution electron microscopy. This is because even a small misalignment of the incident beam direction induces wave aberrations and affects the appearance of high resolution electron micrographs. Some alignment procedures which cancel out the coma by changing the incident beam direction have been proposed. Most recently, the effect of a three-fold astigmatism on the coma-free alignment has been revealed, and new algorithms of coma-free alignment have been proposed.However, the voltage-center and the coma-free alignments as well as the current-center alignment in general do not coincide to each other because of beam deflection due to a leakage field within the objective lens, even if the main magnetic-field of the objective lens is rotationally symmetric. Since all the proposed procedures for the coma-free alignment also use the same beam deflector above the objective lens that is used for the voltage-center alignment, the coma-free alignment is only attained at the sacrifice of the voltage-center alignment.

Structure analysis of amorphous Pd75Si25 alloy by electron diffraction and high-resolution electron microscopy

1996 ◽  
Vol 217-218 ◽  
pp. 392-396 ◽  
Author(s):  
Mitsuhide Matsushita ◽  
Yoshibiko Hirotsu ◽  
Tadakatsu Ohkubo ◽  
Tetsuo Oikawa ◽  
Akihiro Makino
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Electron Diffraction ◽  
Structure Analysis ◽  
High Resolution Electron Microscopy ◽  
Resolution Electron

The Observation Of Mg)-Al Interface By Hrem and Microdiffraction

1985 ◽  
Vol 43 ◽  
pp. 240-241
Author(s):  
S.Y. Zhang ◽  
J.M. Cowley
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
High Resolution ◽  
Materials Science ◽  
Incident Beam ◽  
High Resolution Electron Microscopy ◽  
Interface Structure ◽  
Resolution Electron ◽  
Powerful Means ◽  
Interface Structures

The combination of high resolution electron microscopy (HREM) and nanodiffraction techniques provided a powerful means for characterizing many of the interface structures which are of fundamental importance in materials science. In this work the interface structure between magnesium oxide and aluminum has been examined by HREM (with JEM-200CX) and nanodiffraction (with HB-5). The interfaces were formed by evaporating Al on freshly prepared cubic MgO smoke crystals under various vacuum conditions, at 10 -4, 10-5 10-6 and 10-7 torr. The Al layers on the MgO (001) surface are about 100Å thick. TEM observations were performed with the incident beam along the MgO [100] direction so that the interface could be revealed clearly. The nanodiffraction patterns were obtained with the electron beam of 15Å diameter parallel to the interface.

High-Resolution Electron Microscopy of condensed clusters in a potassium barium oxomolybdate

1994 ◽  
Vol 52 ◽  
pp. 648-649
Author(s):  
R. Ramlau ◽  
G. L. Schimek ◽  
R. E. McCarley ◽  
A. Simon
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Structure Analysis ◽  
High Resolution Electron Microscopy ◽  
General Concept ◽  
Molybdenum Oxides ◽  
Compound K ◽  
Space Group ◽  
X Ray ◽  
Resolution Electron

The recently synthesized compound K0.19Ba3.81Mo22O34 is a representative of the ternary and quaternary reduced molybdenum oxides in which clusters built from molybdenum octahedra are arranged in layers of composition AxByMo4n+2O6n+4. The number of trans-edgesharing molybdenum octahedra in the cluster is represented by n. The general concept of cluster condensation is formulated and discussed elsewhere. For K0.19Ba3.81Mo22O34, n is equal to 5. A ternary representative, likewise with n = 5, is In6Mo22O34.By x-ray structure analysis, K0.19Ba3.81Mo22O34 proved to crystallize in space group P21/a with parameters a = 0.9908(2) nm, b = 0.9353(2) nm, c = 1.5951(3) nm, and β = 98.78(2)°. The potassium atoms were found to reside on the same sites as the barium atoms with an almost statistical distribution.We studied K0.19Ba3.81Mo22O34 by high-resolution electron microscopy (HREM). Small fragments of a crystal were investigated using a Philips CM30/ST microscope operating at 300 kV (point resolution 0.19 nm). At appropriate orientations of the crystal fragments, HREM images reveal domains of two ordered polytypes: a monoclinic and an orthorhombic one (Figs. 1 and 2).

Structure Analysis of Ni-Silicides Formed in Lateral Diffusion Couples

1984 ◽  
Vol 37 ◽  
Author(s):  
S. H. Chen ◽  
J. C. Barbour ◽  
L. R. Zheng ◽  
C. B. Carter ◽  
J. W. Mayer
Keyword(s):  
Electron Microscopy ◽  
Phase Diagram ◽  
High Resolution ◽  
Structure Analysis ◽  
Composition Range ◽  
Lateral Diffusion ◽  
High Resolution Electron Microscopy ◽  
The Other ◽  
Diffusion Couples ◽  
Resolution Electron

AbstractThe microstructures of the silicide Ni5Si2, which formed in self-supporting Ni-Si lateral-diffusion couples has been studied using high-resolution electron microscopy. Two different polymorphs (or polytypes) for Ni5Si2 have been observed. The actual composition of one polytype is confirmed to be Ni31Si12, while the other one has not yet been identified. Variations in the distribution of the two polytypes, as observed in the present study, may account for the composition range of Ni5Si2 in the Ni-Si phase diagram.

On the interpretation of electron diffraction patterns from materials containing planar boundaries: the intergrowth tungsten bronzes

1990 ◽  
Vol 429 (1876) ◽  
pp. 91-117 ◽  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Electron Diffraction ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
General Interest ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Resolution Imaging ◽  
Diffraction Patterns

Materials containing planar boundaries are of general interest and complete understanding of their structures is important. When direct imaging of the boundaries by, for instance, high-resolution electron microscopy, is impracticable, details of their structure and arrangement may be obtained from electron diffraction patterns. Such patterns are discussed in terms of those from intergrowth tungsten bronzes as specific examples. Fourier-transform calculations for proposed structures have been made to establish, in conjunction with optical-diffraction analogues, the features of the far-field diffraction patterns. These results have been compared with diffraction patterns obtained experimentally by transmission electron microscopy. The aim of the study, to show that the arrangement of the boundaries in these complicated phases can be deduced from their diffraction patterns without the need for high-resolution imaging, has been achieved. The steps to be taken to make these deductions are set out.

Detection of Point Defect Chains in Ion Irradiated Silicon by High Resolution Electron Microscopy

1980 ◽  
Vol 2 ◽  
Author(s):  
W. Krakow ◽  
T.Y. Tan ◽  
H. Foell
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Point Defect ◽  
Image Matching ◽  
Imaging Study ◽  
High Resolution Electron Microscopy ◽  
Structure Model ◽  
Lattice Imaging ◽  
Resolution Electron ◽  
Chain Type

ABSTRACTIn a lattice imaging study of As+ ion damaged Si, we have detected =110> chain type defects which are not associated with any significant strain or configurational changes. By image matching of the experimental and calculated micrographs of vacancies and interstitials, it is established that about 100% more interstitial atoms may incorporate into a defective chain. A structure model of this defect is proposed wherein a di-interstitial, occupying the =100> split position, is incorporated into every available site along a =110> chain.

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