Computed Structures of [001] Symmetrical Tilt Boundaries in Covalently Bonded Materials

1985 ◽  
Vol 63 ◽  
Author(s):  
J. T. Wetzel ◽  
A. A. Levi ◽  
D. A. Smith
Keyword(s):  
Grain Boundary ◽  
Silicon Germanium ◽  
Computer Modelling ◽  
Field Potential ◽  
Boundary Structure ◽  
Bonded Materials ◽  
Grain Boundary Structure ◽  
Covalently Bonded ◽  
Tilt Boundaries ◽  
Symmetrical Tilt

ABSTRACTThe dependence of the structure of (210) and (310) symmetrical [001] tilt boundaries in silicon, germanium and diamond on the Keating covalent force field (potential) has been investigated by computer modelling. We have found that the sensitivity of grain boundary structure to variations of the Keating potential depends on the local atomic arrangement at the grain boundary.

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.

Direct Determination of Grain Boundary Atomic Structure in SrTiO3

1994 ◽  
Vol 357 ◽  
Author(s):  
M.M. McGibbon ◽  
N.D. Browning ◽  
A.J. McGibbon ◽  
M.F. Chisholm ◽  
S.J. Pennycook
Keyword(s):  
Grain Boundary ◽  
Atomic Structure ◽  
Light Element ◽  
Direct Determination ◽  
Atomic Scale ◽  
Boundary Structure ◽  
Structure Property ◽  
Contrast Imaging ◽  
Grain Boundary Structure ◽  
Tilt Boundaries

AbstractIn the electroceramic SrTiO3 the grain boundary atomic structure governs a variety of electrical properties such as non-linear I-V characteristics. An understanding of this atomic structure-property relationship for individual grain boundaries requires a technique which probes both composition and chemical bonding on an atomic scale. Atomic structure models for [001] tilt boundaries in SrTiO3 bicrystals have been determined directly from experimental data, by combining high-resolution Z-contrast imaging to locate the cation columns at the boundary, with simultaneous electron energy loss spectroscopy to examine light element coordination at atomic resolution. In this paper we compare and contrast the grain boundary structure models of symmetric and asymmetric boundaries in SrTiO3.

On the structure of tilt grain boundaries in cubic metals I. Symmetrical tilt boundaries

1983 ◽  
Vol 309 (1506) ◽  
pp. 1-36 ◽  
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Hydrostatic Stress ◽  
Stress Fields ◽  
Boundary Structure ◽  
Structural Elements ◽  
Cubic Metals ◽  
Short Period ◽  
Tilt Boundaries ◽  
Symmetrical Tilt

An atomistic study of tilt grain boundary structures in f.c.c. metals has been made. The principal aim of this study is to understand the structure of long-period (‘general’) tilt boundaries. Boundaries for which Σ< 491 were considered, where Σ is the reciprocal density of coincidence sites. The work is presented in three parts. In this paper three series of atomistic studies of symmetrical tilt boundaries in aluminium and copper are reported. One of the main objectives is to determine whether the stress fields of localized grain boundary dislocations exist in boundaries deviated far from any short-period boundary orientations. On the basis of the results of these studies, a new structural classification of grain boundaries is introduced. Certain boundaries are found to be the fundamental structural elements of other boundaries nearby in the misorientation range. Boundaries that consist of contiguous sequences of one type of fundamental structural elements are called favoured; all other boundaries are called non-favoured. Itis found that favoured boundaries are not always associated with the lowest possible values of Σ and that the same boundaries are not necessarily favoured in all metals with the same crystal structure. With use of the pair interactions to calculate the atomic level stress tensor, the hydrostatic stress fields of the boundaries are displayed. In all cases considered the stress fields of distinct, localized intrinsic grain boundary dislocations were found in non-favoured boundaries. The concept of continuity of boundary structure with misorientation is introduced. It is shown that continuity of boundary structure requires unique boundary structures at all misorientations. With use of this concept it is demonstrated how one can predict the atomic structure and stress field of any non-favoured boundary between two known, successive favoured boundaries. It is also found that an isolated discontinuous change in boundary structure between two successive favoured boundaries may exist, depending on their translation states. Some earlier atomistic studies of tilt boundaries in f.c.c. and b.c.c. metals are reinterpreted in the light of this work.

Two Investigations into Grain Boundary Structure

1977 ◽  
Vol 35 ◽  
pp. 688-691
Author(s):  
P. Humble
Keyword(s):  
Grain Boundary ◽  
Dark Field ◽  
Boundary Structure ◽  
Boundary Dislocation ◽  
Bright Field ◽  
Intrinsic Structure ◽  
Weak Beam ◽  
Grain Boundary Structure ◽  
Independent Information ◽  
Diffraction Patterns

There has been sustained interest over the last few years into both the intrinsic (primary and secondary) structure of grain boundaries and the extrinsic structure e.g. the interaction of matrix dislocations with the boundary. Most of the investigations carried out by electron microscopy have involved only the use of information contained in the transmitted image (bright field, dark field, weak beam etc.). Whilst these imaging modes are appropriate to the cases of relatively coarse intrinsic or extrinsic grain boundary dislocation structures, it is apparent that in principle (and indeed in practice, e.g. (1)-(3)) the diffraction patterns from the boundary can give extra independent information about the fine scale periodic intrinsic structure of the boundary.In this paper I shall describe one investigation into each type of structure using the appropriate method of obtaining the necessary information which has been carried out recently at Tribophysics.

Relationships Between Grain Boundary Structure and Material Properties

1980 ◽  
Vol 38 ◽  
pp. 366-369
Author(s):  
Brian Ralph ◽  
Barlow Claire ◽  
Nicola Ecob
Keyword(s):  
Grain Boundary ◽  
Material Properties ◽  
Main Property ◽  
Grain Structure ◽  
Boundary Structure ◽  
Grain Boundary Structure ◽  
Property Changes

This brief review seeks to summarize some of the main property changes which may be induced by altering the grain structure of materials. Where appropriate an interpretation is given of these changes in terms of current theories of grain boundary structure, and some examples from current studies are presented at the end of this paper.

ELECTRON MICROSCOPE STUDIES OF GRAIN BOUNDARY STRUCTURE IN CUBIC METALS

1975 ◽  
Vol 36 (C4) ◽  
pp. C4-17-C4-22 ◽  
Author(s):  
R. W. BALLUFFI ◽  
P. J. GOODHEW ◽  
T. Y. TAN ◽  
W. R. WAGNER
Keyword(s):  
Electron Microscope ◽  
Grain Boundary ◽  
Boundary Structure ◽  
Cubic Metals ◽  
Grain Boundary Structure
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