Structural multiplicity in a tilt boundary in germanium

1988 ◽  
Vol 46 ◽  
pp. 592-593
Author(s):  
D.A. Smith ◽  
Z. Elgat ◽  
W. Krakow ◽  
A.A. Levi ◽  
C.B. Carter
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Twin Boundary ◽  
Atomic Structure ◽  
Czochralski Method ◽  
Tilt Boundary ◽  
Considerable Progress ◽  
Related Structure ◽  
First Order ◽  
Impurity Segregation

There has been considerable progress made recently in understanding the atomic structure of grain boundaries in metals, semiconductors and ceramics. There is still, however, some dispute over whether a given grain boundary can exist with more than one non-symmetry-related structure. This has been shown experimentally to be the case in Ge for the first-order twin boundary lying parallel to the lateral {112} plane. In the present paper, it will be shown that a similar result holds for a more general grain boundary (actually Σ=137) lying close to the Σ=19 orientation; the Σ=19 boundary is formed by a rotation of 26.5° about a common <110> direction and lies along a common {31} plane. It is thus likely that a similar result will hold for other grain boundaries.Since it is essential to know that the different structures are not due to impurity segregation effects, bicrystals were grown from the melt with pre-oriented seeds using the Czochralski method following the approach of Bacmann as modified at Cornell by Skrotzki et al.

The Structure of Grain Boundaries and Phase Boundaries in Ceramics

1983 ◽  
Vol 31 ◽  
Author(s):  
C. B. Carter
Keyword(s):  
Grain Boundaries ◽  
Twin Boundary ◽  
Tilt Boundary ◽  
Twist Boundary ◽  
Phase Boundaries ◽  
Large Unit ◽  
First Order ◽  
Unit Cells ◽  
Ionic Nature

ABSTRACTThe structure of different grain boundaries and phase boundaries are discussed by reference to a series of specific examples. The chosen examples of grain boundaries include the <l10>{l10} tilt boundary, the (001) twist boundary and the first-order twin boundary in spinel and the basal twin and the (1123) twin in Al2O3 . The phase boundaries discussed are the β'''-alumina/spinel interface, the wustite/spinel interface and the spinel/alumina interface. It is shown that these interfaces do have properties which result specifically from the ionic nature of the material and the large unit cells involved in each case.

Morphology and atomic structure of segregated grain boundaries in Cu-Sb

1992 ◽  
Vol 50 (1) ◽  
pp. 254-255
Author(s):  
R. W. Fonda ◽  
D. E. Luzzi
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Intergranular Fracture ◽  
Atomic Structure ◽  
Copper Alloys ◽  
Polycrystalline Materials ◽  
Grain Boundary Embrittlement ◽  
Boundary Embrittlement

The properties of polycrystalline materials are strongly dependant upon the strength of internal boundaries. Segregation of solute to the grain boundaries can adversely affect this strength. In copper alloys, segregation of either bismuth or antimony to the grain boundary will embrittle the alloy by facilitating intergranular fracture. Very small quantities of bismuth in copper have long been known to cause severe grain boundary embrittlement of the alloy. The effect of antimony is much less pronounced and is observed primarily at lower temperatures. Even though moderate amounts of antimony are fully soluble in copper, concentrations down to 0.14% can cause grain boundary embrittlement.

Σ =13 tilt grain boundary in silicon bicrystal

1990 ◽  
Vol 48 (4) ◽  
pp. 562-563
Author(s):  
M.J. Kim ◽  
Y.L. Chen ◽  
R.W. Carpenter ◽  
J.C. Barry ◽  
G.H. Schwuttke
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Rotation Axis ◽  
Czochralski Method ◽  
High Resolution Electron Microscopy ◽  
Image Simulation ◽  
Simulation Techniques ◽  
Resolution Electron ◽  
The Common ◽  
Tilt Grain Boundary

The structure of grain boundaries (GBs) in metals, semiconductors and ceramics is of considerable interest because of their influence on physical properties. Progress in understanding the structure of grain boundaries at the atomic level has been made by high resolution electron microscopy (HREM) . In the present study, a Σ=13, (510) <001>-tilt grain boundary in silicon was characterized by HREM in conjunction with digital image processing and computer image simulation techniques.The bicrystals were grown from the melt by the Czochralski method, using preoriented seeds. Specimens for TEM observations were cut from the bicrystals perpendicular to the common rotation axis of pure tilt grain boundary, and were mechanically dimpled and then ion-milled to electron transparency. The degree of misorientation between the common <001> axis of the bicrystal was measured by CBED in a Philips EM 400ST/FEG: it was found to be less than 1 mrad. HREM was performed at 200 kV in an ISI-002B and at 400 kv in a JEM-4000EX.

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.

Structure and Dissociation of 15° Tilt Boundaries in Germanium

1983 ◽  
Vol 25 ◽  
Author(s):  
W. Skrotzki ◽  
H. Wendt ◽  
C. B. Carter ◽  
D. L. Kohlstedt
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Boundary ◽  
Czochralski Method ◽  
Boundary Plane ◽  
First Order ◽  
Grain Boundary Plane ◽  
Transmission Electron ◽  
Theoretical Predictions ◽  
Tilt Boundaries

ABSTRACTThe structure and dissociation of grain boundaries in Ge bicrystals, grown by the Czochralski method, have been analyzed by visible light and transmission electron microscopy. The seed crystals were oriented to yield either a symmetric or an asymmetric grain boundary plane with a 15° rotation about a common <110> direction. The asymmetric boundary, with a {111} boundary plane, dissociated along most of its length into a first order twin boundary (Σ 3) and a symmetric 55° grain boundary (Σ 41c). The symmetric 15° boundary is composed of an array of Lomer dislocations. Contrary to theoretical predictions, this boundary is stable.

Quantum-Chemical Simulation of Silicon Grain Boundaries Contaminated by Oxygen and Carbon

2005 ◽  
Vol 108-109 ◽  
pp. 235-240
Author(s):  
Anis M. Saad ◽  
Alex L. Pushkarchuk ◽  
A.V. Mazanik ◽  
A.K. Fedotov ◽  
S.A. Kuten
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Conduction Band ◽  
Atomic Structure ◽  
Quantum Chemical ◽  
Electronic States ◽  
Quantum Chemical Simulation ◽  
The Core ◽  
Chemical Simulation

Transformation of the “core” atomic structure and electronic states of the tilt Σ5 θ = 37° [001]/(130) grain boundary in poly-Si due to incorporation of carbon atoms into the oxygencontaining complexes is studied using MM and MO LCAO methods. Different numbers n = 1 ÷ 4 of C-atoms were introduced into the 5-fold interstitial positions in the initial O-containing complexes built-up from SiO3 and SiO4 configurations at the GB “core”. Incorporation of C-atoms into SiO3 and SiO4 complexes leads to the formation of Si-O-C-Si chains and shifting of the donorlike levels generated by SiO3 and SiO4 configurations to the bottom of the conduction band with an increase in the number of the incorporated C-atoms.

Ionic Conductivities and Microstructures of CeO2:Y203 Solid Electrolytes

1998 ◽  
Vol 548 ◽  
Author(s):  
Chunyan Tian ◽  
Siu-Wai Chan
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Solid Electrolytes ◽  
Dopant Concentration ◽  
Ionic Conductivities ◽  
Oxygen Depletion ◽  
Boundary Conductivity ◽  
Size Dependent ◽  
Impurity Segregation ◽  
Microanalytical Technique

ABSTRACTIonic conductivities of solid CeO2:Y203 electrolytes were systematically investigated as a function of dopant concentration and sintering temperatures. The highest lattice conductivity occurred at 6–8% dopant concentration, and maximum grain boundary conductivity was observed at 10% dopant concentration. The sintering temperature was found to have a significant effect on the conductivities of the pellets. The samples sintered at lower temperatures (T≤140°C) showed higher grain boundary conductivity than those sintered at 150°C; this was found to be related to size-dependent-impurity segregation and precipitation at grain boundaries. The grain boundary conductivities as related to the microstructure are discussed by adopting different grain boundary models. Solute segregation and oxygen depletion at grain boundaries, which have been suggested to be responsible for the grain boundary resistivities in these samples, were examined by a microanalytical technique for small-grain-size samples.

Energies and Atomic Structures of Grain Boundaries in Diamond: Comparison With Grain Boundaries in Silicon

1994 ◽  
Vol 339 ◽  
Author(s):  
M. Kohyama ◽  
H. Ichinose ◽  
Y. Ishida ◽  
M. Nakanose
Keyword(s):  
Thin Films ◽  
Grain Boundaries ◽  
Interfacial Energy ◽  
Atomic Structure ◽  
Tight Binding ◽  
Tilt Boundary ◽  
Atomic Structures ◽  
Fundamental Properties ◽  
Diamond Thin Films ◽  
First Time

ABSTRACTFairly different features of grain boundaries in diamond from those in Si were experimentally observed in diamond thin films. As the first step in order to understand the fundamental properties of grain boundaries in diamond, the energy and atomic structure of the {122} σ=9 tilt boundary have been calculated for the first time by using the tight-binding electronic theory. The results have been compared with the calculations of the same boundary and the {111} σ=3 boundary in Si. It has been shown that the σ=9 boundary in diamond has a very large interfacial energy caused by the large bond rigidity as compared with the boundaries in Si and the {111}σ=3 boundary in diamond. This point should be related to the observation that the {122}σ =9 boundary is rarely found in diamond thin films.

Interfaces Part II: Mechanical and High-Temperature Behavior

MRS Bulletin ◽  
1990 ◽  
Vol 15 (10) ◽  
pp. 23-25 ◽  
Author(s):  
Dieter Wolf ◽  
Sidney Yip
Keyword(s):  
High Temperature ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Fracture Behavior ◽  
Boundary Energy ◽  
Temperature Behavior ◽  
Boundary Structure ◽  
Elastic Response ◽  
High Temperature Behavior ◽  
Impurity Segregation

This is the second of two issues of the MRS BULLETIN on interface materials and is entirely devoted to their mechanical and high-temperature behavior. Mechanical properties provide a rich area for investigating the effect of the local inhomogeneities near the interfaces, and their effect on the interrelation between the structure and chemistry on one hand, and the elastic and fracture behavior on the other.Based on much experimental work on grain-boundary fracture it seems that, with the exception of “beneficial” segregants, the embrittlement potential of most impurities is governed by their propensity for segregation to the grain boundaries, which in turn is strongly influenced by the energies of the pure boundaries. To investigate the role of the grain-boundary structure in its fracture behavior, one must therefore consider the correlations between (1) the structure (i.e., the five macroscopic degrees of freedom) and the energy of pure grain boundaries, (2) impurity segregation and the grain boundary energy, (3) structure, impurity segregation and elastic response at the interface, and finally (4) the correlation between embrittlement and segregation. In addition, the mobility of dislocations near a crack tip also plays an important role. Unfortunately, relatively little knowledge has been accumulated on most of these complex interrelations even though their unraveling is widely recognized as the ultimate goal.

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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