The Atomic Structure Of The Zn-Mg-Rare-Earth Quasicrystals Studied By High-Resolution Electron Microscopy

1998 ◽  
Vol 553 ◽  
Author(s):  
Eiji Abe ◽  
An Pang Tsai
Keyword(s):  
Electron Microscopy ◽  
Rare Earth ◽  
High Resolution ◽  
Atomic Structure ◽  
Structural Model ◽  
Symmetry Plane ◽  
Atomic Clusters ◽  
Icosahedral Symmetry ◽  
Structural Description ◽  
Penrose Tiling

AbstractHigh-resolution transmission electron microscopy has been applied to study the real atomic structure of the decagonal (d-) quasicrystal in the Zn-Mg-rare-earth (RE) system, which is the first d-phase based on Frank-Kasper phase. We show that the phase has a novel structure in which the atomic arrangement in the tenfold symmetry plane can simply be interpreted as the Penrose tiling decorated by individual atoms - the simplest realization of the Penrose tiling as a real atomic structure. This is supported by the fact that a similar local atomic configuration exists in the Zn7Mg4 crystal structure. This simple structural model is in sharp contras to the idea of atomic clusters, which has been successfully used to describe the structure of quasicrystals in Altransition metal alloys. The present results strongly suggest that the symmetric atomic clusters are not an essential factor for formation of quasicrystals. Instead, a new idea of quasi-unit-cell and its covering is applied for structural description. The atomic structure of the Zn-Mg-RE icosahedral phase is also implied to follow the present concept, based on the fact that its related crystalline phases with hexagonal lattices are not built of giant atomic clusters with icosahedral symmetry.

Atomic structure imaging of the Si/SiO2 interface with high-resolution electron microscopy

1986 ◽  
Vol 44 ◽  
pp. 390-391
Author(s):  
J.L. Batstone ◽  
J.M. Gibson ◽  
Alice.E. White ◽  
K.T. Short
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Atomic Structure ◽  
High Resolution Electron Microscopy ◽  
Medium Voltage ◽  
Voltage Electron ◽  
Resolution Electron ◽  
Structural Image ◽  
Electron Microscopes ◽  
Point To Point

High resolution electron microscopy (HREM) is a powerful tool for the determination of interface atomic structure. With the previous generation of HREM's of point-to-point resolution (rpp) >2.5Å, imaging of semiconductors in only <110> directions was possible. Useful imaging of other important zone axes became available with the advent of high voltage, high resolution microscopes with rpp <1.8Å, leading to a study of the NiSi2 interface. More recently, it was shown that images in <100>, <111> and <112> directions are easily obtainable from Si in the new medium voltage electron microscopes. We report here the examination of the important Si/Si02 interface with the use of a JEOL 4000EX HREM with rpp <1.8Å, in a <100> orientation. This represents a true structural image of this interface.

Quantitative High Resolution Electron Microscopy of Grain Boundaries and Comparison with Atomistic Simulations

2001 ◽  
Vol 7 (S2) ◽  
pp. 244-245
Author(s):  
G.H. Campbell ◽  
W.E. King ◽  
J.M. Plitzko ◽  
J. Belak ◽  
S.M. Foiles
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Grain Boundaries ◽  
Atomic Structure ◽  
Radiation Effects ◽  
Crystal Defects ◽  
Boundary Structure ◽  
Atomistic Simulations ◽  
Simulated Image ◽  
Good Test

The technique of high-resolution transmission electron microscopy (HREM) produces images that contain information about the atomic structure of the specimen. Within additional, very stringent, constraints, the HREM image can contain information about atomic structure of crystal defects, including grain boundaries and interfaces. to extract this information from the image it is necessary to compare the experimental image with a simulated image calculated based upon an atomic model of the specimen.2 in this comparison, investigators have been aided by the use of quantitative techniques.Atomistic simulations are often used to predict the atomic structure of crystal defects or to simulate the evolution of dynamic processes in crystals, e.g. radiation effects or dislocation motion and interaction. During the development of new models of interatomic interactions, the predictions of simulations are tested against experimental observations to validate new potentials. Grain boundary structure is a good test because atoms residing in the boundary experience environments (interatomic distances and angles) that are significantly different from those experienced by atoms residing in a perfect crystal lattice site.

High-resolution transmission electron microscopy study of the φ′- and δ-AlON spinel phases of the pseudo-binary section AlN–Al2O3

1999 ◽  
Vol 32 (4) ◽  
pp. 755-760 ◽  
Author(s):  
P. Tabary ◽  
C. Servant ◽  
M. Guymont
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Structural Model ◽  
Spinel Phase ◽  
High Resolution Electron Microscopy ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Resolution Electron ◽  
Spinel Phases ◽  
Binary Section

A previously proposed structural model [Tabary & Servant (1999).J. Appl. Cryst.32, 253–272] for the φ′- and δ-AlON spinel phases, which allows for the double modulation of composition and displacement of cations and anions and which describes both phases and their relationships to the γ-AlON spinel phase, is here supported by high-resolution electron microscopy observations.

Atomic Structure of Interfaces in Epitaxial NiSi2 on (001) Silicon

1992 ◽  
Vol 263 ◽  
Author(s):  
W.J. Chen ◽  
F.R. Chen ◽  
L.J. Chen
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Atomic Structure ◽  
Imaging Technique ◽  
Interface Structure ◽  
High Resolution Imaging ◽  
Image Simulation ◽  
Transmission Electron ◽  
Resolution Imaging ◽  
Boundary Core

ABSTRACTHigh resolution transmission electron microscopy (HRTEM) has been applied to study the atomic structure of NiSi2 /(001)Si interface. Previous HRTEM result suggested that Ni atoms in the boundary core are six-fold coordinated and Si atoms are everywhere tetrahedrally coordinated. In this work, high resolution imaging technique and computer image simulation were used to study the atomic structure of NiSi2 /(001)Si interfaces and a new interface structure was found. For the new interface structure, Ni and Si atoms are also six-fold and tetrahedrally coordinated, respectively, with an extra layer of fourfold planar bonded Si atoms present at the interface.

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