On Geometric Models for Interphase Boundaries

1990 ◽  
Vol 187 ◽  
Author(s):  
Hans J. Fecht
Keyword(s):  
Atomic Structure ◽  
Chemical Interaction ◽  
Low Energy ◽  
Geometric Models ◽  
Lattice Matching ◽  
Metal Metal ◽  
Interphase Boundaries ◽  
Static Distortion ◽  
Lock In ◽  
Energy Configurations

AbstractThe energy interphase boundaries can be described as a function of the lattice matching at the interface between two adjacent crystals, the chemical interaction and the interfacial entropy of the boundaries. Geometric models relating the energy of interphase boundaries (metal/metal and metal/non-metal) to their atomic structure can be based on the static distortion wave concept. This approach constitutes the physical basis for the lock-in model and the planar CSL-model proposed previously to describe the low energy configurations of such interfaces.

Atomic Structure of Heterophase Boundaries

1990 ◽  
Vol 202 ◽  
Author(s):  
Hans J. Fecht
Keyword(s):  
Atomic Structure ◽  
Low Energy ◽  
Physical Basis ◽  
Geometric Models ◽  
Static Distortion ◽  
Energy Configurations

ABSTRACTGeometric models relating the energy of heterophase boundaries to their atomic structure can be based on the static distortion wave concept. This approach allows to separate the energetic contributions of commensurate and incommensurate boundary structures and provides the physical basis for models proposed previously to predict low energy configurations of such interfaces.

Quasiperiodic interfaces: HREM observations of grain and phase boundaries

1990 ◽  
Vol 48 (4) ◽  
pp. 332-333
Author(s):  
K. L. Merkle
Keyword(s):  
Atomic Structure ◽  
Direct Determination ◽  
Lattice Parameter ◽  
Atomic Scale ◽  
Misfit Dislocations ◽  
Oxide Systems ◽  
Atomic Structures ◽  
Periodic Arrays ◽  
Parameter Ratio ◽  
Metal Metal

The atomic structures of internal interfaces have recently received considerable attention, not only because of their importance in determining many materials properties, but also because the atomic structure of many interfaces has become accessible to direct atomic-scale observation by modem HREM instruments. In this communication, several interface structures are examined by HREM in terms of their structural periodicities along the interface.It is well known that heterophase boundaries are generally formed by two low-index planes. Often, as is the case in many fcc metal/metal and metal/metal-oxide systems, low energy boundaries form in the cube-on-cube orientation on (111). Since the lattice parameter ratio between the two materials generally is not a rational number, such boundaries are incommensurate. Therefore, even though periodic arrays of misfit dislocations have been observed by TEM techniques for numerous heterophase systems, such interfaces are quasiperiodic on an atomic scale. Interfaces with misfit dislocations are semicoherent, where atomically well-matched regions alternate with regions of misfit. When the misfit is large, misfit localization is often difficult to detect, and direct determination of the atomic structure of the interface from HREM alone, may not be possible.

CHEMICAL RECONSTRUCTION OF THE TiAl(010) SURFACE

1995 ◽  
Vol 02 (02) ◽  
pp. 183-189 ◽  
Author(s):  
C.P. WANG ◽  
S.K. KIM ◽  
F. JONA ◽  
D.R. STRONGIN ◽  
B.-R. SHEU ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Atomic Structure ◽  
Atomic Layer ◽  
Interlayer Spacing ◽  
Low Energy ◽  
Intensity Analysis ◽  
Low Energy Electron Diffraction ◽  
Surface Phases ◽  
Low Energy Electron ◽  
Bulk Structure

The atomic structure of a clean (010) surface of the ordered binary alloy TiAl (with tetragonal bulk structure of the CuAu I type) is studied with quantitative low-energy electron diffraction (QLEED). Two different surface phases are found depending on the preparation procedure. After a cleaning step in vacuo by means of Ar-ion bombardments, anneals at 750−850°C produce a 2×1 surface and anneals at about 900° C produce a 1×1 surface. A QLEED intensity analysis of the 1×1 structure reveals the occurrence of chemical reconstruction, whereby the Ti atoms in the first layer exchange places with the Al atoms in the second layer. Thus, while any bulk (010) plane contains 50% Al and 50% Ti , the top atomic layer of a (010) surface contains 100% Al and the second atomic layer contains 100% Ti . Both layers are slightly buckled and the first interlayer distance is compressed about 7.1% while the second interlayer spacing is expanded about 7.4% with respect to the bulk value.

Derivative Spectra of Very Low Energy Photoelectrons from CO/Cu(001) Surface Obtained by a Lock-in Technique

2006 ◽  
Vol 75 (10) ◽  
pp. 104303 ◽  
Author(s):  
Kei Hayashi ◽  
Ryuichi Arafune ◽  
Shigenori Ueda ◽  
Yoichi Uehara ◽  
Sukekatsu Ushioda
Keyword(s):  
Low Energy ◽  
Derivative Spectra ◽  
Lock In

scholarly journals Atomic Structure of Domain and Interphase Boundaries in Ferroelectric HfO2

2018 ◽  
Vol 5 (5) ◽  
pp. 1701258 ◽  
Author(s):  
Everett D. Grimley ◽  
Tony Schenk ◽  
Thomas Mikolajick ◽  
Uwe Schroeder ◽  
James M. LeBeau
Keyword(s):  
Atomic Structure ◽  
Interphase Boundaries

STUDIES OF FINDING LOW ENERGY CONFIGURATIONS IN OFF-LATTICE PROTEIN MODELS

2006 ◽  
Vol 05 (03) ◽  
pp. 587-594 ◽  
Author(s):  
JINGFA LIU ◽  
WENQI HUANG
Keyword(s):  
Lower Energy ◽  
Gradient Descent ◽  
Energy Landscape ◽  
Three Dimensional ◽  
Ground States ◽  
Low Energy ◽  
Protein Models ◽  
Energy Configurations ◽  
Energy Landscape Paving ◽  
Lattice Protein Models

We studied two three-dimensional off-lattice protein models with two species of monomers, hydrophobic and hydrophilic. Low energy configurations in both models were optimized using the energy landscape paving (ELP) method and subsequent gradient descent. The numerical results show that the proposed methods are very promising for finding the ground states of proteins. For all sequences with lengths 13 ≤ n ≤ 55, the algorithm finds states with lower energy than previously proposed putative ground states.

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