High-resolution imaging of symmetric tilt and mixed character boundaries in Al

1990 ◽  
Vol 48 (4) ◽  
pp. 336-337
Author(s):  
M. Shamzuzzoha ◽  
P.A. Deymier ◽  
David J. Smith
Keyword(s):  
High Resolution ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Thin Foil ◽  
Polycrystalline Materials ◽  
Voltage Electron ◽  
Symmetric Tilt ◽  
Resolution Electron ◽  
Resolution Imaging ◽  
Electron Microscopes

The determination of the core structure of grain boundaries is central to a better understanding of the properties of polycrystalline materials. With the recent advent of intermediate-voltage electron microscopes (300-400kV), it is possible to obtain atomic-resolution images of grain boundaries in many metals - for example, the atomic structure of periodic grain boundaries in selected metals has been studied. Our knowledge of materials properties can be further enhanced by investigating more complex, arbitrarily misoriented grain boundaries. In this paper, we will report HREM imaging of a symmetric tilt low-angle grain boundary and a twist-and-tilt (mixed character) grain boundary in Al.The Al bicrystals used in this study were produced by cross-rolling and annealing methods described in detail elsewhere. Thin foil specimens of 3mm diameter containing specific boundaries were obtained by spark-cutting and subsequent electropolishing in 73% methanol, 25% nitric acid and 2% hydrochloric acid. HREM was performed with a JEM-4000EX operated at 400kV, using axial illumination and without an objective aperture. High-resolution electron micrographs were recorded near the optimum defocus, typically at a magnification of 500,000 times.

Characterization of Grain Boundaries and Interfaces by High Resolution Transmission Electron Microscopy

1989 ◽  
Vol 153 ◽  
Author(s):  
William Krakow
Keyword(s):  
High Resolution ◽  
Grain Boundaries ◽  
Ohmic Contacts ◽  
Dielectric Material ◽  
Medium Voltage ◽  
Voltage Electron ◽  
Resolution Electron ◽  
Interfacial Structures ◽  
Tilt Boundaries ◽  
Electron Microscopes

AbstractSeveral examples will be given of high resolution electron microscope images of both grain boundaries and interfaces and the methods which have been applied to understanding their atomic structure. Specific expitaxial interfacial structures considered are: Pd2Si/Si used for ohmic contacts, Al on Si overlayers and CaF2/Si where the CaF2, is an attractive possibility as a dielectric material. For the case of grain boundaries specific examples of both twist and tilt boundaries in Au will be given to show the imaging capability with the new generation of medium voltage electron microscopes.

Characterization of structural units in tilt grain boundaries

1992 ◽  
Vol 50 (1) ◽  
pp. 120-121
Author(s):  
Stuart McKernan ◽  
C. Barry Carter
Keyword(s):  
High Resolution ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
High Resolution Electron Microscopy ◽  
Boundary Structure ◽  
Structural Units ◽  
Symmetric Tilt ◽  
Resolution Electron ◽  
Special Cases ◽  
High Resolution Electron Microscope

General tilt grain boundaries can be viewed in terms of small structural units of varying complexity. High-resolution electron microscope (HREM) images of these boundaries in many materials show this repetitive similarity of the atomic structure at the boundary plane. The structure of particular grain boundaries has been examined for several special cases and commonly observed configurations include symmetric tilt grain boundaries and asymmetric tilt grain boundaries with one grain having a prominent, low-index facet. Several different configurations of the boundary structure may possibly occur, even in the same grain boundary. There are thus many possible ways to assemble the basic structural units to form a grain boundary. These structural units and their distribution have traditionally been examined by high-resolution electron microscopy. The images of the projection of the atomic columns (or the tunnels between atomic columns) providing a template for constructing “ball-and-stick ” models of the interface.

Atomic structure imaging of the Si/SiO2 interface with high-resolution electron microscopy

1986 ◽  
Vol 44 ◽  
pp. 390-391
Author(s):  
J.L. Batstone ◽  
J.M. Gibson ◽  
Alice.E. White ◽  
K.T. Short
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Atomic Structure ◽  
High Resolution Electron Microscopy ◽  
Medium Voltage ◽  
Voltage Electron ◽  
Resolution Electron ◽  
Structural Image ◽  
Electron Microscopes ◽  
Point To Point

High resolution electron microscopy (HREM) is a powerful tool for the determination of interface atomic structure. With the previous generation of HREM's of point-to-point resolution (rpp) >2.5Å, imaging of semiconductors in only <110> directions was possible. Useful imaging of other important zone axes became available with the advent of high voltage, high resolution microscopes with rpp <1.8Å, leading to a study of the NiSi2 interface. More recently, it was shown that images in <100>, <111> and <112> directions are easily obtainable from Si in the new medium voltage electron microscopes. We report here the examination of the important Si/Si02 interface with the use of a JEOL 4000EX HREM with rpp <1.8Å, in a <100> orientation. This represents a true structural image of this interface.

Surface studies in UHV: Applications of High-resolution electron microscopy

1991 ◽  
Vol 49 ◽  
pp. 444-445
Author(s):  
M. R. McCartney ◽  
David J. Smith
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
High Vacuum ◽  
High Resolution Electron Microscopy ◽  
Plan View ◽  
Voltage Electron ◽  
Resolution Electron ◽  
Video Systems ◽  
Electron Microscopes

The examination of surfaces requires not only that they be free of adsorbed layers but the environment of the sample must also be maintained at high vacuum so that the surfaces remain clean. The possibility of resolving surface structures with atomic resolution has provided the motivation for optimizing intermediate and high voltage electron microscopes for this particular application. Electron microscopy offers a variety of techniques which have the capability of achieving atomic level detail of surfaces including plan-view imaging, REM and profile imaging. Operation at higher voltages permits reasonable pole piece dimensions thereby providing space for in situ studies yet still compatible with high resolution. Moreover, video systems can be attached which permit observation and recording of dynamic phenomena without compromising microscope performance.

Hrem on Grain Boundaries in Oxide Superconductors

1989 ◽  
Vol 156 ◽  
Author(s):  
H.W. Zandbergenl ◽  
G. van Tendeloo
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Grain Boundaries ◽  
Amorphous Material ◽  
High Resolution Electron Microscopy ◽  
Critical Currents ◽  
Polycrystalline Materials ◽  
Oxide Superconductors ◽  
Resolution Electron ◽  
Superconducting Oxides

ABSTRACTHigh resolution electron microscopy has been carried out on grain boundaries in a number of superconducting oxides: YBa2Cu3O77−∂, LaCaBaCu3O7−∂, Bi2Sr2CanCun+1O2n+6+∂, and Pb2(Sr, Ca)3−xAxCu2+nO6+2n+∂. In general no amorphous material or another phase is observed at the grain boundaries. It is argued that the low critical currents in these polycrystalline materials are caused by the atomic structure of (001) interfaces at grain boundaries and concerning YBa2Cu3O7 and LaCaBaCu3O7−∂ by the intercalation of CuO layers starting from the grain boundaries.

Grain Boundary Transformations in Bi-Doped Copper

1991 ◽  
Vol 238 ◽  
Author(s):  
Elsie C. Urdaneta ◽  
David E. Luzzi ◽  
Charles J. McMahon
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Treatment Time ◽  
High Resolution Electron Microscopy ◽  
Transmission Electron ◽  
Resolution Electron

ABSTRACTBismuth-induced grain boundary faceting in Cu-12 at ppm Bi polycrystals was studied using transmission electron microscopy (TEM). The population of faceted grain boundaries in samples aged at 600°C was observed to increase with heat treatment time from 15min to 24h; aging for 72h resulted in de-faceting, presumably due to loss of Bi from the specimen. The majority of completely faceted boundaries were found between grains with misorientation Σ=3. About 65% of the facets of these boundaries were found to lie parallel to crystal plane pairs of the type {111}1/{111]2- The significance of these findings in light of recent high resolution electron microscopy experiments is discussed.

Possible evidence for overcoordination at semiconductor grain boundaries

1990 ◽  
Vol 5 (3) ◽  
pp. 587-592 ◽  
Author(s):  
W. Krakow ◽  
A. A. Levi ◽  
S. T. Pantelides
Keyword(s):  
High Resolution ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Experimental Evidence ◽  
Screw Dislocation ◽  
Electron Micrograph ◽  
Resolution Electron ◽  
Tilt Grain Boundary

The structure of a near coincidence Ge tilt grain boundary, containing a step, has been derived from a high resolution electron micrograph. There are two possible interpretations of portions of this interface, one of which is the existence of a sheet of fivefold coordinated atoms between the Σ = 19 and Σ = 27 coincidence misorientations. This finding may represent the first experimental evidence that overcoordinated atoms are present at semiconductor grain boundaries free of a screw dislocation.

Structure of the ∑=3 (111) Grain Boundary in Cu-1.5%Sb

1992 ◽  
Vol 295 ◽  
Author(s):  
Richard W. Fonda ◽  
David E. Luzzi
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Auger Electron ◽  
Preliminary Investigation ◽  
High Resolution Electron Microscopy ◽  
Transmission Electron ◽  
Resolution Electron

AbstractGrain boundaries in quenched and aged Cu-i.5%Sb were examined with Auger electron microscopy, transmission electron microscopy, and high resolution electron microscopy. The ∑=3 grain boundaries are strongly faceted, with the facets lying primarily along the coincident (111) planes of the two grains. The grain boundaries are enriched in antimony, as demonstrated by both AES and HREM. HREM images of the ∑=3 (111) ║ (111) grain boundary differ from those of the Cu-Bi ∑ =3 (111) ║ (111) grain boundary in the lack of a significant grain boundary expansion to accommodate the excess solute at the boundary. A preliminary investigation of the atomic structure of the ∑=3 (111) ║ (111) facet by HREM and multislice calculations is presented.

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