Atomic structure of a Σ = 21 grain boundary

1990 ◽  
Vol 5 (11) ◽  
pp. 2658-2662 ◽  
Author(s):  
William Krakow
Keyword(s):  
Electron Microscope ◽  
Grain Boundary ◽  
Atomic Structure ◽  
Structural Unit ◽  
Defect Structures ◽  
Atomic Column ◽  
Unit Model ◽  
Tilt Grain Boundary

An electron microscope structure image of a σ = 21/[111] tilt grain boundary in Au was obtained and atomic column positions identified to yield a structural unit model of the interface consisting of repeating polyhedron shapes. This result represents the smallest projected spacings at a grain boundary containing defect structures imaged by an electron microscope and interpreted atomistically.

Atomic Structure of a Symmetric 27°[001] Tilt Grain Boundary in MgO

1997 ◽  
Vol 3 (S2) ◽  
pp. 653-654
Author(s):  
Yanfa Yan ◽  
M. F. Chisholm ◽  
S. J. Pennycook
Keyword(s):  
Grain Boundary ◽  
Atomic Structure ◽  
Fibonacci Sequence ◽  
Scanning Transmission Electron Microscope ◽  
Contrast Imaging ◽  
Atomic Column ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Tilt Grain Boundary ◽  
Z Contrast

The atomic structure of a symmetric 27° [001] tilt grain boundary in MgO has been determined by high-resolution Z-contrast imaging using a 300 kV VG HB603U scanning transmission electron microscope with a 1.3 Å probe. The atomic configuration in the grain boundary core is found to be considerably less open than the structures proposed earlier for similar materials.Fig. 1 shows the Z-contrast image of the grain boundary and the projected structure derived from the image. It is clearly seen that the boundary is a shared plane of atoms with the same atomic column density as a bulk crystal {100} plane. The boundary consists of an array of separated perfect edge dislocation cores with Burgers vector b= a<100>. It is interesting to point out that the spacing between dislocation cores in the boundary is not uniform (as seen in Fig. 2). The arrangement, which follows the Fibonacci sequence, can be accurately predicted.

Atomic Structure of ZnO Σ13 [0001]/{134¯0} Symmetric Tilt Grain Boundary

2013 ◽  
Vol 97 (2) ◽  
pp. 617-621 ◽  
Author(s):  
Ji-Young Roh ◽  
Yukio Sato ◽  
Yuichi Ikuhara
Keyword(s):  
Grain Boundary ◽  
Atomic Structure ◽  
Symmetric Tilt ◽  
Tilt Grain Boundary

Local atomic structure of a near-sigma 5 tilt grain boundary in MgO

2013 ◽  
Vol 48 (16) ◽  
pp. 5470-5474 ◽  
Author(s):  
Mitsuhiro Saito ◽  
Zhongchang Wang ◽  
Susumu Tsukimoto ◽  
Yuichi Ikuhara
Keyword(s):  
Grain Boundary ◽  
Atomic Structure ◽  
Local Atomic Structure ◽  
Tilt Grain Boundary

Atomic structure of a tilt grain boundary in aluminum by HREM

1990 ◽  
Vol 24 (8) ◽  
pp. 1611-1615 ◽  
Author(s):  
M. Shamsuzzoha ◽  
David J. Smith ◽  
P.A. Deymier
Keyword(s):  
Grain Boundary ◽  
Atomic Structure ◽  
Tilt Grain Boundary

Quantitative HREM using non-linear least-squares methods

1994 ◽  
Vol 52 ◽  
pp. 716-717
Author(s):  
Wayne E. King ◽  
Michael A. O’Keefe ◽  
Geoffrey H. Campbell
Keyword(s):  
High Resolution ◽  
Grain Boundary ◽  
Least Squares ◽  
Atomic Structure ◽  
Linear Least Squares ◽  
Electron Microscopic ◽  
Atomic Column ◽  
Imaging Parameters ◽  
Non Linear ◽  
Experimental Image

Non-linear least-squares methods have been coupled with high resolution image simulation to determine the critical electron microscopic imaging parameters, such as thickness and defocus, from an experimental image. The method has been extended to include the optimization of atomic column positions and occupancy to determine atomic structure. As an example, the method has been applied to the refinement of the atomic structure of a Σ5(310)/[001] grain boundary in Nb.In the past, high resolution electron microscopy has been applied in a primarily qualitative manner through the visual comparison of experimental images with simulated images. The potential for more quantitative analysis has been pointed out and recently, increasing attention is being given to more quantitative matching of experiment with simulation. Emphasis is being placed on the deduction of imaging parameters and/or the refinement of atomic structures from experimental images.In this paper, we describe an approach to the optimization of the critical electron-optical imaging parameters of an experimental image and the atomic structure of a crystalline defect, namely a grain boundary.

Atomic structure of undoped Σ=5 symmetrical-tilt grain boundary in strontium titanate

1993 ◽  
Vol 51 ◽  
pp. 986-987
Author(s):  
V. Ravikumar
Keyword(s):  
Grain Boundary ◽  
Strontium Titanate ◽  
Atomic Structure ◽  
Processing Parameters ◽  
Boundary Region ◽  
Boundary Structure ◽  
Reference Structure ◽  
Structure Changes ◽  
Symmetrical Tilt ◽  
Tilt Grain Boundary

Strontium titanate is an important electroceramic material which, under appropriate processing and dopant additions exhibits both varistor and Grain Boundary Layer Capacitor (GBLC) behavior. The presence of electrically active grain boundaries is essential for obtaining these properties. The first step towards correlating the grain boundary structure to properties is to determine the detailed atomic structure of the boundary, which includes its geometric structure, chemistry and electronic structure. We present here our TEM investigation of the atomic structure of an undoped (“pristine”) symmetrical tilt grain boundary in SrTiO3. This provides the basic reference structure, changes to which can be studied as a function of doping and/or processing parameters, and correlated to electrical and dielectric properties.Self-supported TEM samples were made from bicrystals of SrTiO3 through the conventional sample preparation route. Fig. 1 shows a high resolution electron micrograph (Hitachi H9000) of a representative grain boundary region in the sample.

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