Study of the Metamict Transformation in α-Quartz Using High-Resolution Electron Microscopy and Convergent Beam Electron Diffraction

1981 ◽  
Vol 6 ◽  
Author(s):  
M. R. Pascucci ◽  
J. L. Hutchison ◽  
L. W. Hobbs
Keyword(s):  
Electron Microscopy ◽  
Electron Diffraction ◽  
High Resolution Electron Microscopy ◽  
Convergent Beam Electron Diffraction ◽  
Transformation Model ◽  
Beam Electron ◽  
Surrounding Matrix ◽  
Resolution Electron ◽  
Two Stages ◽  
Convergent Beam

ABSTRACTThe metamict transformation under electron irradiation has been studied in α-quartz using transmission electron microscopy (TEM) and convergent-beam electron diffraction (CBD). The transformation occurs in two stages: heterogeneous nucleation of discrete disordered inclusions and a slower homogeneous loss of crystalline order in the surrounding matrix. Both features are attributable to solidstate radiolysis, a mechanism for which is proposed. Ultrahigh resolution TEM structure images and information from zeroth and high order Laue zones in CBD confirm that shortrange correlations are the first to be lost and that longerrange correlations persist well into the metamict transformation. A transformation model is advanced in which progressive disorder evolves from small displacements of individual [SiO4] coordination units, made possible by lowered connectivity, within a framework of long-range ordered material.

scholarly journals Microstructure of High Temperature Superconductors of the Perovskite Type

1987 ◽  
Vol 40 (4) ◽  
pp. 547 ◽  
Author(s):  
AF Moodie ◽  
HJ Whitfield
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
High Temperature Superconductor ◽  
High Temperature Superconductors ◽  
High Resolution Electron Microscopy ◽  
Convergent Beam Electron Diffraction ◽  
Beam Electron ◽  
Resolution Electron ◽  
Convergent Beam ◽  
Perovskite Type

Combined high resolution electron microscopy and convergent beam electron diffraction (CBED) of the same areas of crystals of Ba3La3Cu6014 reveals defects of various types including ordinary dislocations and polytypic intergrowths. This latter type is considered to be intimately associated with the performance of this material as a high temperature superconductor ..

The Structure of GaAs Grown by Chemical Beam Epitaxy on Low-Temperature Cleaned Silicon

1992 ◽  
Vol 281 ◽  
Author(s):  
Y. R. Xing ◽  
C. J. Kiely ◽  
P. J. Goodhew
Keyword(s):  
Electron Microscopy ◽  
Low Temperature ◽  
Defect Density ◽  
High Resolution Electron Microscopy ◽  
Convergent Beam Electron Diffraction ◽  
Chemical Beam Epitaxy ◽  
Beam Electron ◽  
Resolution Electron ◽  
Convergent Beam

ABSTRACTChemical beam epitaxy (CBE) has been used to grow GaAs on silicon with a low defect density after etching in HF followed by a low temperature (600°C) in situ heat treatment. High resolution electron microscopy (HREM) and convergent beam electron diffraction (CBED) studies show the presence of 90° and 60° dislocations and some inversion domains.

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