Structural relation between a 2D fivefold quasicrystal and crystalline approximants in an Al–Co–Ni–Tb alloy

1996 ◽  
Vol 11 (8) ◽  
pp. 1891-1896 ◽  
Author(s):  
X. Z. Li ◽  
K. Hiraga
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Two Dimensional ◽  
Large Unit ◽  
Atom Cluster ◽  
Aperiodic Tiling ◽  
Resolution Electron ◽  
Microscopy Image ◽  
Large Unit Cell

A two-dimensional quasicrystal with fivefold symmetry and two large-unit-cell crystalline approximants in an Al–Co–Ni–Tb alloy, which were observed in previous studies, are suggested to be composed of the same kind of atom cluster. Some characteristics of the atom cluster can be deduced from a high-resolution electron microscopy image of the Al–Co–Ni–Tb quasicrystal when the image is associated with a fivefold aperiodic tiling. By using the cut-and-projection method, a quasiperiodic tiling generated by an irrational projection is proposed as an ideal quasilattice of the Al–Co–Ni–Tb quasicrystal; in the meantime, periodic tilings generated by a rational projection present the lattices of the crystalline approximants.

Cubic silicon nitride embedded in amorphous silicon dioxide

2001 ◽  
Vol 16 (8) ◽  
pp. 2179-2181
Author(s):  
Ming Zhang ◽  
Hongliang He ◽  
F. F. Xu ◽  
T. Sekine ◽  
T. Kobayashi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Silicon Nitride ◽  
High Resolution ◽  
Analytical Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Cubic Symmetry ◽  
Resolution Electron ◽  
Microscopy Image ◽  
Wave Compression ◽  
Small Crystallite

A cubic silicon nitride embedded in amorphous SiO2 compound has been characterized by means of high-resolution analytical electron microscopy. The specimen was prepared from β–Si3N4 powders at a high pressure and temperature by shock wave compression. The typical high-resolution electron microscopy image from one small crystallite together with its diffractodiagram pattern indicated that the Si3N4 crystallites had a cubic symmetry. The electron energy loss spectrum from the small crystallite is very different from those of outside amorphous SiO2 phase and raw β–Si3N4 particles, and there are more N elements that were detected in this small crystallite than those in standard Si3N4.

Recent trends in high-resolution electron microscopy

1986 ◽  
Vol 44 ◽  
pp. 530-533
Author(s):  
David J. Smith
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Two Dimensional ◽  
Planar Defects ◽  
Medium Voltage ◽  
Resolution Electron ◽  
Routine Basis ◽  
Recent Trends ◽  
Electron Microscopes

The recent advent of high-resolution electron microscopes (HREMs) capable of resolving sub-2-Ångstrom detail on a routine basis has led to an enormous increase in the range of materials which can be usefully studied. Not only is it possible to resolve individual atomic columns in low index zones of most common metals but observations of semiconductors, for example, are no longer restricted to the traditional [110] zone, thereby making it feasible at last to obtain two-dimensional information about surfaces, interfaces and other planar defects. There is a worldwide upsurge of interest in the capabilities of these machines and the so-called medium-voltage (300-400kV) HREMs are selling rapidly despite their considerable expense. Our objective here is to provide a brief and selective overview of the latest applications and likely trends in HREM studies of materials - further details can be found elsewhere in these proceedings. No attempt is made to review instrumentation developments since they are being considered separately.

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