The dislocation structure of a 10° [110] tilt boundary in silicon

1983 ◽  
Vol 41 ◽  
pp. 114-115
Author(s):  
B. Cunningham ◽  
D.G. Ast
Keyword(s):  
Dislocation Structure ◽  
Tilt Angle ◽  
Imaging Technique ◽  
Diamond Lattice ◽  
Tilt Boundary ◽  
Formation Mechanisms ◽  
Diffraction Contrast ◽  
Lattice Fringe ◽  
Tilt Boundaries ◽  
Chemically Vapor Deposited

There have Been a number of studies of low-angle, θ < 4°, [10] tilt boundaries in the diamond lattice. Dislocations with Burgers vectors a/2<110>, a/2<112>, a<111> and a<001> have been reported in melt-grown bicrystals of germanium, and dislocations with Burgers vectors a<001> and a/2<112> have been reported in hot-pressed bicrystals of silicon. Most of the dislocations were found to be dissociated, the dissociation widths being dependent on the tilt angle. Possible dissociation schemes and formation mechanisms for the a<001> and a<111> dislocations from the interaction of lattice dislocations have recently been given.The present study reports on the dislocation structure of a 10° [10] tilt boundary in chemically vapor deposited silicon. The dislocations in the boundary were spaced about 1-3nm apart, making them difficult to resolve by conventional diffraction contrast techniques. The dislocation structure was therefore studied by the lattice-fringe imaging technique.

TEM Study of a Tilt Boundary in Hot-Pressed Silicon

1981 ◽  
Vol 39 ◽  
pp. 160-161
Author(s):  
C. B. Carter ◽  
J. Rose ◽  
D. G. Ast
Keyword(s):  
Electron Diffraction ◽  
Imaging Technique ◽  
Interface Structure ◽  
Large Area ◽  
Weak Beam ◽  
Lattice Fringe ◽  
Electron Diffraction Technique ◽  
Tilt Boundaries ◽  
Beam Technique ◽  
Twist Boundaries

The hot-pressing technique which has been successfully used to manufacture twist boundaries in silicon has now been used to form tilt boundaries in this material. In the present study, weak-beam imaging, lattice-fringe imaging and electron diffraction techniques have been combined to identify different features of the interface structure. The weak-beam technique gives an overall picture of the geometry of the boundary and in particular allows steps in the plane of the boundary which are normal to the dislocation lines to be identified. It also allows pockets of amorphous SiO2 remaining in the interface to be recognized. The lattice-fringe imaging technique allows the boundary plane parallel to the dislocation to be identified. Finally the electron diffraction technique allows the periodic structure of the boundary to be evaluated over a large area - this is particularly valuable when the dislocations are closely spaced - and can also provide information on the structural width of the interface.

The Suitability Of The Lattice Fringe Imaging Technique For Measuring Spatial Variation In Degree Of Long-Range Order In Fe-Al Alloys

1977 ◽  
Vol 35 ◽  
pp. 184-185
Author(s):  
Samuel M. Allen
Keyword(s):  
Long Range ◽  
Imaging Technique ◽  
Superlattice Reflection ◽  
Dynamical Theory ◽  
Al Alloys ◽  
Range Order ◽  
Long Range Order ◽  
Lattice Fringe ◽  
Feal Phase ◽  
Simulated Images

A computer simulation of lattice fringe imaging of ordered Fe-Al alloys has been carried out, using the multiple beam dynamical theory of electron diffraction as formulated by Sinclair et al. for CU3AU (1). The object of the study was to determine the suitability of the lattice fringe imaging technique for studying spatial variations in long-range order parameter in singlephase ordered specimens.In the interest of simplicity, the results of simulations in which eight beams were excited in the (200) systematic row for an imperfectly B2-ordered alloy of composition Fe-25% aluminum will be presented. (The prototype crystal structure for the FeAl phase is CsCl.) Simulated images were obtained by combining the direct beam with the (100) superlattice reflection, for the case in which Bragg's Law was satisfied for the (100) reflection, and with both beams equidistant from the optic axis of the microscope.Image intensities as a function of distance parallel to [200] were computed for different specimen thicknesses and long-range order parameters.

The Study of Grain Boundaries in Ceramics by Electron Diffraction

1980 ◽  
Vol 38 ◽  
pp. 370-373
Author(s):  
C.B. Carter
Keyword(s):  
Grain Boundaries ◽  
Imaging Techniques ◽  
Amorphous Material ◽  
Ceramic Materials ◽  
Boundary Region ◽  
Dark Field ◽  
Intimate Contact ◽  
Diffraction Contrast ◽  
Weak Beam ◽  
Lattice Fringe

Grain boundaries are particularly important in polycrystalline ceramics since it is found experimentally that the properties of the grain boundary region control many properties of the material. In ceramic materials, most interfaces between adjacent grains appear to take one of two forms: they can have a periodic structure if the two grains are in intimate contact - such boundaries would be similar to boundaries observed in metals; or there may be a film of amorphous material present in the interface - the width of such a film may be as little as ~lnm. it is also possible that a second crystalline phase is present at the boundary or, of course, the structure of the interface may consist of a combination of these. Until recently the main techniques used for studying grain boundaries in ceramics have been the strong-beam bright-field and weak-beam dark-field modes of diffraction contrast and lattice-fringe imaging techniques. Diffraction contrast techniques are particularly valuable for studying grain boundaries composed of dislocations where the dislocation spacing is greater than ~15nm or ~4nm for strong-beam and weak-beam respectively. The lattice-fringe imaging technique has been particularly valuable for the identification of boundaries which contain thin films of amorphous material. An additional technique using diffuse scattered electrons to study such boundaries has been shown to be susceptible to misinterpretation when the specimen is coated to prevent charging in the microscope.

scholarly journals Effect of Grain Boundary Structure on Grain Boundary Diffusivities in the Au/Ag System

1990 ◽  
Vol 209 ◽  
Author(s):  
Qing Ma ◽  
R. W. Balluffi
Keyword(s):  
Thin Film ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Tilt Angle ◽  
Structural Unit ◽  
Boundary Structure ◽  
Grain Boundary Structure ◽  
Unit Model ◽  
Tilt Boundaries ◽  
Accumulation Method

ABSTRACTGrain boundary chemical diffusivities for a series of symmetric [001] tilt boundaries in the Au/Ag system were measured by the surface accumulation method using newly developed thin-film multi-crystal specimens, in which the grain boundaries feeding the accumulation surface were all of the same type. Possible effects due to segregation at the grain boundaries and surfaces were avoided. CSL boundaries of low-Σ ( i.e., 5, 13, 17, 25) and also more general boundaries with tilt angles between the low-Σ orientations were selected. The diffusivities were found to vary monotonically with tilt angle ( i.e., no cusps at low-Σ's were found) in a manner consistent with the Structural Unit model.

An Atomistic Study of the Equilibrium Segregation of Hydrogen to Tilt Boundaries in Nickel

1991 ◽  
Vol 229 ◽  
Author(s):  
N. R. Moody ◽  
S. M. Foiles
Keyword(s):  
Hydrogen Concentration ◽  
Site Occupancy ◽  
Binding Energies ◽  
Tilt Boundary ◽  
Boundary Structure ◽  
Trap Site ◽  
High Hydrogen ◽  
Embedded Atom ◽  
Concentration Enhancement ◽  
Tilt Boundaries

AbstractIn this study, Monte Carlo simulations have been combined with Embedded Atom Method (EAM) calculations to study hydrogen segregation at the atomic level in an ideal nickel lattice with a Σ9 tilt boundary. The calculations indicate that trap binding energies exceed 0.5 eV on the tilt boundary, but decrease rapidly with distance. Furthermore, the calculations show that trap site occupancy increases with trap site binding energy and hydrogen activity, and reach saturation at high hydrogen concentrations. Most importantly, significant rearrangements in tilt boundary structure are predicted to occur as hydrogen concentration increases. The results are consistent with observations that show significant hydrogen concentration enhancement at grain boundaries in nickel and palladium. They also parallel the effect of hydrogen concentration on crack growth susceptibility in nickel and iron-rich alloys. However, the change in boundary structure as hydrogen concentration increases challenges our understanding of hydrogen-induced fracture.

Grain Boundary Structure and Its Energy of Symmetric Tilt Boundary in Copper

2004 ◽  
Vol 467-470 ◽  
pp. 807-812 ◽  
Author(s):  
Naoki Takata ◽  
Kenichi Ikeda ◽  
Fusahito Yoshida ◽  
H. Nakashima ◽  
Hiroshi Abe
Keyword(s):  
Grain Boundary ◽  
Free Volume ◽  
Atomic Structure ◽  
Boundary Energy ◽  
Tilt Boundary ◽  
Grain Boundary Energy ◽  
Structural Units ◽  
Symmetric Tilt ◽  
Tilt Boundaries ◽  
Symmetric Tilt Boundary

In the present study, grain boundary energy and atomic structure of <110> symmetric tilt boundaries in copper were evaluated by molecular dynamics (MD) simulation. From the simulations, the grain boundary energy of <110> symmetric tilt boundaries depended on misorientation angle and there were large energy cusps at the misorientation angles which corresponded to (111) S 3 and (113) S 11 symmetric tilt boundaries. It was found that the atomic structure of each <110> symmetric tilt boundary was described by the combination of three kinds of structural units which consisted of (331) S 19, (111) S 3 and (113) S 11 symmetric tilt boundaries and two single crystal units which consisted of (110) S 1and (001) S 1 single crystals. From the the analysis of the excess free volume in each grain boundary, it was found that the energy of structural units depended on the excess free volume of the units and that the misorientation dependence of grain boundary energy agreed with that of the free volume in grain boundaries.

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