John Maxwell Cowley 1923 - 2004

2006 ◽  
Vol 17 (2) ◽  
pp. 227
Author(s):  
A. F. Moodie ◽  
J. C. H. Spence
Keyword(s):  
Electron Microscopy ◽  
Electron Diffraction ◽  
Electron Scattering ◽  
Scanning Transmission Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Dynamical Theory ◽  
X Rays ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Scanning Transmission

John Cowley contributed significantly to all of the fields that relate to electron diffraction and electron microscopy, and helped to found not a few of them. His name is associated in particular with n-beam dynamical theory, high-resolution electron microscopy, scanning transmission electron microscopy, instrumental design, and the application of the techniques of electron scattering to structure analysis. His experimental work was not, however, confined to the scattering of electrons: to take but one instance, his seminal work on the theory of short-range order was stimulated initially by his experiments using X-rays, and it was only later that he extended the technique to include electron diffraction. Finally, to all those who practise the techniques of scattering electrons, X-rays, or neutrons in the study of solids, liquids or gases, his book Diffraction Physics remains not only eminently readable but authoritative.

Effect of niobium on the oxidation behavior of TiAl

2007 ◽  
Vol 22 (6) ◽  
pp. 1486-1490 ◽  
Author(s):  
Wei Lu ◽  
ChunLin Chen ◽  
LianLong He ◽  
YanJun Xi ◽  
FuHui Wang
Keyword(s):  
Electron Microscopy ◽  
Scanning Transmission Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Potential Effect ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Scanning Transmission ◽  
Nb Doping ◽  
Z Contrast ◽  
Contrast Image

Two TiO2layers formed in TiAl oxidation for 50 h at 900 °C were studied using scanning transmission electron microscopy. The main efforts were placed on the investigation of the distribution of niobium. It was found that Nb enriched in TiO2grains of mixture layer but did not exist in the outer TiO2layer. High-resolution electron microscopy (HREM) Z-contrast image revealed that Nb substitute for Ti site leading to Nb enrichment in TiO2grains of the mixture layer. The formation mechanism of the two TiO2layers and the potential effect of Nb doping in the mixture layer were also discussed.

AlN Nanorods synthesized by a Mechanothermal Process

2011 ◽  
Vol 1288 ◽  
Author(s):  
G. Rosas ◽  
J. Chihuaque ◽  
C. Patiño-Carachure ◽  
R. Esparza ◽  
R. Pérez
Keyword(s):  
Electron Microscopy ◽  
Mechanical Milling ◽  
Annealing Treatment ◽  
High Resolution Electron Microscopy ◽  
Dynamical Theory ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Structural Configurations ◽  
Simulated Images

ABSTRACTWell-crystallized AlN nanorods have been produced by mechanical milling and subsequent annealing treatment of the milling powders (mechanothermal process). High purity AlN powders were used as the starting material. Mechanical milling was carried out in a vibratory SPEX mill for 30 h, using vials and balls of silicon nitride. The annealing treatment was carried out at 1200 ºC for 10 min. The characterization of the samples was performed by X-ray diffractometry and transmission electron microscopy (TEM). TEM observations indicated that the synthesized nanorods consisted of 30 nm in diameter and 100 nm in length. High resolution electron microscopy observations have been used in the structural characterization. AlN nanorods exhibit a well-crystallized structure. The growing direction of the nanorods is close to the [001] direction. The structural configurations have been explored through comparisons between experimental HREM images and theoretically simulated images obtained with the multislice method of the dynamical theory of electron diffraction.

scholarly journals Combining Scanning Transmission Electron Microscopy and Electron Diffraction to Understand the Atomic Structures of Oxide Superlattices

2011 ◽  
Vol 17 (S2) ◽  
pp. 1078-1079
Author(s):  
A Shah ◽  
B Nelson-Cheeseman ◽  
A Bhattacharya ◽  
J-M Zuo ◽  
J Spence
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Diffraction ◽  
Scanning Transmission Electron Microscopy ◽  
Atomic Structures ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

scholarly journals Electron Microscopy for Atomic/Electronic Structure of Quasicrystals

2014 ◽  
Vol 70 (a1) ◽  
pp. C1193-C1193
Author(s):  
Eiji Abe
Keyword(s):  
Electron Microscopy ◽  
Electronic Structure ◽  
Scanning Transmission Electron Microscopy ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Aperiodic Order ◽  
Scanning Transmission ◽  
High Resolution Electron Microscope ◽  
Diffraction Patterns ◽  
Key Questions

As stated with special emphasis in the Noble Lecture by Dr. Shechtman, the quasicrystal discovery is definitely the victory of electron microscopy – the first icosahedral stereogram was constructed by a series of electron diffraction patterns from a tiny quasicrystalline grain, and the following high-resolution electron microscope images indeed confirmed a unique aperiodic order that can never be consistent with twinning of normal crystals. Almost thirty years after these early electron microscopy studies, we are now in the era of aberration-corrected electron microscopy which realizes a remarkable resolution beyond an Ångstrom scale [1, 2]. In the talk, I will describe the local atomic/electronic structure of quasicrystals using state-of-the-art scanning transmission electron microscopy, providing several striking insights that may lead to the answers for the longstanding key questions; "Where are the atoms? And why do quasicrystals form?"

Unstained Biological Specimens in High Resolution Electron Microscopy

1974 ◽  
Vol 32 ◽  
pp. 234-235
Author(s):  
M. K. Lamvik ◽  
J. M. Pullman ◽  
A. V. Crewe
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Heavy Atom ◽  
High Resolution Electron Microscopy ◽  
Scanning Transmission Electron Microscope ◽  
Dark Field ◽  
Structural Studies ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Scanning Transmission

Negative staining and high resolution shadowing have been extensively used for structural studies in electron microscopy. However, these techniques cover the specimen with a layer of heavy salt or metal, and hence do not allow determination of true mass distribution or localization of specific sites using heavy atom markers. A prerequisite for such structural studies is an examination of unstained specimens. For thin specimens dark field microscopy must be used to obtain adequate contrast. The scanning transmission electron microscope is preferred for such studies since elastic, energyloss, and unscattered electrons can be recorded and analyzed quantitatively to form images with a minimum of beam-induced damage.

Change of Nanostructure in (Fe0.5Co0.5)72B20Si4Nb4 Metallic Glass on Annealing

2007 ◽  
Vol 539-543 ◽  
pp. 2077-2081 ◽  
Author(s):  
Akihiko Hirata ◽  
Yoshihiko Hirotsu ◽  
Kenji Amiya ◽  
Nobuyuki Nishiyama ◽  
Akihisa Inoue
Keyword(s):  
Electron Microscopy ◽  
Electron Diffraction ◽  
Development Process ◽  
Glassy Alloy ◽  
High Resolution Electron Microscopy ◽  
Intensity Analysis ◽  
Diffraction Intensity ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Bulk Glassy Alloy

Nanoscale structural change in (Fe0.5Co0.5)72B20Si4Nb4 bulk glassy alloy on annealing has been investigated using transmission electron microscopy. On annealing at temperatures above 773K, electron diffraction intensity analysis showed a clear structure change for a Cr23C6-type local atomic ordering. The local structure formation of Cr23C6-type nanophase was confirmed by nanobeam electron diffraction. A development process of dense precipitates of the Cr23C6-type nanophase was further studied by high-resolution electron microscopy. It was found that the formation of the highly-dense nanoprecipitates provides an increase in Vickers hardness.

On the interpretation of electron diffraction patterns from materials containing planar boundaries: the intergrowth tungsten bronzes

1990 ◽  
Vol 429 (1876) ◽  
pp. 91-117 ◽  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Electron Diffraction ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
General Interest ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Resolution Imaging ◽  
Diffraction Patterns

Materials containing planar boundaries are of general interest and complete understanding of their structures is important. When direct imaging of the boundaries by, for instance, high-resolution electron microscopy, is impracticable, details of their structure and arrangement may be obtained from electron diffraction patterns. Such patterns are discussed in terms of those from intergrowth tungsten bronzes as specific examples. Fourier-transform calculations for proposed structures have been made to establish, in conjunction with optical-diffraction analogues, the features of the far-field diffraction patterns. These results have been compared with diffraction patterns obtained experimentally by transmission electron microscopy. The aim of the study, to show that the arrangement of the boundaries in these complicated phases can be deduced from their diffraction patterns without the need for high-resolution imaging, has been achieved. The steps to be taken to make these deductions are set out.

Sign in / Sign up

Export Citation Format

Share Document