The hierarchy of grain boundary structures in SiC bicrystals

1988 ◽  
Vol 46 ◽  
pp. 596-597
Author(s):  
Y. Ishida ◽  
H. Ichinose ◽  
Y. Inomata
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Lattice Theory ◽  
Coincidence Site Lattice ◽  
Boundary Structure ◽  
Geometrical Theory ◽  
Site Lattice ◽  
Atomic Structures ◽  
Grain Boundary Structure ◽  
Predictive Role

The standard geometrical theory having been developed to describe periodically ordered grain boundaries in metals, ie coincidence-site lattice theory faces a new frontier to be expanded in terms of hierarchy of atomic structures in low energy grain boundaries of polytype SiC bicrystals. The unit translation lattice of the polytype crystal is large and elongated in the direction perpendicular to the basal plane. With the elongated translation lattice, the coincidence-site lattice is generally very large. Often too large to be physically significant, although the predictive role of the coincidence-site lattice theory in specifying the orientation of periodically ordered interface was still preserved. Such periodically ordered boundaries were indeed found to occur in the present SiC bicrystals as is predicted by the geometrical theory. A dual description of the grain boundary structure in terms of hierarchy of atomic structures is shown useful in characterizing the bicrystal boundaries.High purity SiC bicrystals were produced by sublimation-deposition method by cooling the encapseled SiC slowly from 2800K.

Observations and implications of grain boundary dislocation networks in high-angle YBa2Cu3O7−δ grain boundaries

1990 ◽  
Vol 5 (5) ◽  
pp. 919-928 ◽  
Author(s):  
S. E. Babcock ◽  
D. C. Larbalestier
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Weak Link ◽  
Coincidence Site Lattice ◽  
Boundary Structure ◽  
High Angle ◽  
Grain Boundary Structure ◽  
Transmission Electron ◽  
Means Of Transmission ◽  
Regular Networks

Regular networks of localized grain boundary dislocations (GBDs) have been imaged by means of transmission electron microscopy in three different types of high-angle grain boundaries in YBa2Cu3O7-δ, implying that these boundaries possess ordered structures upon which a significant periodic strain field is superimposed. The occurrence of these GBD networks is shown to be consistent with the GBD/Structural Unit and Coincidence Site Lattice (CSL)/Near CSL descriptions for grain boundary structure. Thus, these dislocations appear to be intrinsic features of the boundary structure. The spacing of the observed GBDs ranged from ∼10 nm to ∼100 nm. These GBDs make the grain boundaries heterogeneous on a scale that approaches the coherence length and may contribute to their weak-link character by producing the “superconducting micro-bridge” microstructure which has been suggested on the basis of detailed electromagnetic measurements on similar samples.

First-Principles Studies on Grain Boundary Energies of [110] Tilt Grain Boundaries in Aluminum

2007 ◽  
Vol 561-565 ◽  
pp. 1837-1840 ◽  
Author(s):  
Y. Inoue ◽  
Tokuteru Uesugi ◽  
Yorinobu Takigawa ◽  
Kenji Higashi
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Atomic Structure ◽  
First Principles ◽  
Boundary Structure ◽  
First Principles Calculations ◽  
Atomic Structures ◽  
Grain Boundary Structure ◽  
Transmission Electron ◽  
Tilt Grain Boundary

The grain boundary structure and its energy are necessary for the fundamental understanding of the physical properties of materials. In aluminum, three distinct atomic structures of a Σ9(221)[110] tilt grain boundary have been reported in previous studies using atomistic simulations and a high-resolution transmission electron microscopy (HRTEM). In this work, we studied the atomic structure and energy of the Σ9 tilt grain boundary in aluminum using first-principles calculations. A comparison of the grain boundary energies among the three distinct Σ9 tilt grain boundaries determined through first-principles calculations allowed us to identify the most stable atomic structure of Σ9 tilt grain boundary in aluminum.

Finding the Right Problems: Some HREM Applications to Interfaces

1984 ◽  
Vol 42 ◽  
pp. 376-379
Author(s):  
D. Cherns
Keyword(s):  
Grain Boundaries ◽  
High Resolution Electron Microscopy ◽  
Boundary Structure ◽  
Atomic Structures ◽  
Grain Boundary Structure ◽  
Resolution Electron ◽  
Point To Point ◽  
The Right ◽  
New Generation ◽  
Better Than

The use of high resolution electron microscopy (HREM) to determine the atomic structure of grain boundaries and interfaces is a topic of great current interest. Grain boundary structure has been considered for many years as central to an understanding of the mechanical and transport properties of materials. Some more recent attention has focussed on the atomic structures of metalsemiconductor interfaces which are believed to control electrical properties of contacts. The atomic structures of interfaces in semiconductor or metal multilayers is an area of growing interest for understanding the unusual electrical or mechanical properties which these new materials possess. However, although the point-to-point resolutions of currently available HREMs, ∼2-3Å, appear sufficient to solve many of these problems, few atomic models of grain boundaries and interfaces have been derived. Moreover, with a new generation of 300-400kV instruments promising resolutions in the 1.6-2.0 Å range, and resolutions better than 1.5Å expected from specialist instruments, it is an appropriate time to consider the usefulness of HREM for interface studies.

Structural and Mechanical Properties of Nanophase Ni: A Molecular-Dynamics Study of the Influence of Grain-Boundary Structure on Elastic and Plastic Behavior

1997 ◽  
Vol 492 ◽  
Author(s):  
H. Van Swygenhoven ◽  
M. Spaczér ◽  
A. Caro
Keyword(s):  
Molecular Dynamics ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Diffusion Mechanism ◽  
Distribution Functions ◽  
Boundary Structure ◽  
Plastic Behavior ◽  
Self Diffusion ◽  
Common Neighbour ◽  
Grain Boundary Structure

ABSTRACTMolecular dynamics computer simulations of high load plastic deformation at temperatures up to 500K of Ni nanophase samples with mean grain size of 5 nm are reported. Two types of samples are considered: a polycrystal nucleated from different seeds, each having random location and random orientation, representing a sample with mainly high angle grain boundaries, and polycrystals with seeds located at the same places as before, but with a limited missorientation representing samples with mainly low angle grain boundaries. The structure of the grain boundaries is studied by means of pair distribution functions, coordination number, atom energetics, and common neighbour analysis. Plastic behaviour is interpreted in terms of grain-boundary viscosity, controlled by a self diffusion mechanism at the disordered interface activated by thermal energy and stress.

Systematic Study of Grain Boundary Structure and Chemical Analysis of [100] and [111] Tilt Grain Boundaries in Yttria-Stabilized Zirconia

2004 ◽  
Vol 10 (S02) ◽  
pp. 304-305 ◽  
Author(s):  
James P Buban ◽  
Katsuyuki Matsunaga ◽  
Takahisa Yamamoto ◽  
Yuichi Ikuhara
Keyword(s):  
Chemical Analysis ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Systematic Study ◽  
Yttria Stabilized Zirconia ◽  
Boundary Structure ◽  
Stabilized Zirconia ◽  
Grain Boundary Structure

Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.

GRAIN BOUNDARIES: PHASE TRANSITIONS AND CRITICAL PHENOMENA

1991 ◽  
Vol 05 (19) ◽  
pp. 2989-3028 ◽  
Author(s):  
E.I. RABKIN ◽  
L.S. SHVINDLERMAN ◽  
B.B. STRAUMAL
Keyword(s):  
Phase Transitions ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Critical Phenomena ◽  
External Surface ◽  
Theoretical Models ◽  
Boundary Structure ◽  
Boundary Phase ◽  
Recent Experimental Data ◽  
Grain Boundary Structure

Recent theories of grain boundary structure have been reviewed briefly. The possibility of existence of the same variety of phase transitions on grain boundaries as that on the crystal external surface has been demonstrated. Recent experimental data and theoretical models concerning grain boundary phase transitions are critically analysed. Grain boundary phase transitions connected with the formation of thin disordered layers on the boundary (prewetting, premelting) are particularly distinguished. Results of recent indirect experiments, which may be treated in terms of prewetting and premelting, have been reviewed. Experimentally observed critical phenomena in the vicinity of the prewetting transition on the tin-germanium interphase boundary have been discussed in terms of the critical exponents theory. Some ideas regarding directions of further research are presented.

The Morphology of Grain Boundary Interactions with Twins in YBa2Cu3O7−δ

1993 ◽  
Vol 319 ◽  
Author(s):  
Jenn-Yue Wang ◽  
A. H. King
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Twin Boundary ◽  
Interfacial Energy ◽  
Coincidence Site Lattice ◽  
The Other ◽  
Twin Boundaries ◽  
Site Lattice ◽  
Dislocation Arrays

AbstractVarious morphologies are observed where twins meet grain boundaries in YBa2Cu3O7−δ. Twins may be “correlated” at the boundary (i.e. twin boundaries from one grain may meet a twin boundary from the other grain in a quadruple junction) and the twins may be narrowed or “constricted” at the boundary. These effects are determined by the interfacial energy. We estimate the energy of the various interfaces by determining the dislocation arrays they contain, using the constrained coincidence site lattice (CCSL) model and Bollmann's O2-lattice formalism. Our approach indicates that there are significant changes in the energy of the interfaces and is thus able to explain the variety of observed morphologies.

Sign in / Sign up

Export Citation Format

Share Document