Determination of Layer Structure in Sr1-La TiO3+0.5 (0 < x < 1) Compounds by High-Resolution Electron Microscopy

1995 ◽  
Vol 117 (1) ◽  
pp. 88-96 ◽  
Author(s):  
M.E. Bowden ◽  
D.A. Jefferson ◽  
I.W.M. Brown
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Layer Structure ◽  
High Resolution Electron Microscopy ◽  
Resolution Electron

Microstructural determination of a metastable phase during rhodium oxidation

1989 ◽  
Vol 47 ◽  
pp. 262-263
Author(s):  
A. David Logan
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Volume Expansion ◽  
Lattice Structure ◽  
Metastable Phase ◽  
Active Surface ◽  
High Resolution Electron Microscopy ◽  
Silica Spheres ◽  
Resolution Electron

In heterogeneous catalysis, oxidation of the catalyst is frequently used as a means of removing impurities from the active surface. However, bulk oxidation severely alters the microstructure of the metal due to atom repositioning and valence changes. Transformation of Rh to Rh2O3 causes the lattice structure to change from fcc to hexagonal with a resulting volume expansion of 90% due to density changes. This is the reported cause for fracturing of crystallites and variations in reactivity. In this study, microstructural changes during progressive oxidation of 5 nm metal Rh particles have been examined.A 2 wt% Rh/Silica catalyst was prepared using Rh(III)-2,4 pentanedionate as a precursor and nonporous silica spheres as a support. The catalyst was then reduced in flowing H2 at 473 K. High resolution electron microscopy (HREM) was performed on a JEM-4000EX having a point resolution of 0.17 nm. The catalyst was oxidized in research purity O2 (Matheson 99.99%) using an all glass volumetric chemisorption system.

Image Deconvolution - An Effective Tool of Crystal Structure and Defect Determination in High-Resolution Electron Microscopy

2009 ◽  
Vol 1184 ◽  
Author(s):  
Fanghua Li ◽  
Chunyan Tang
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Image Deconvolution ◽  
One Dimensional ◽  
Modulated Structures ◽  
Resolution Electron ◽  
Different Types

AbstractImage deconvolution is introduced as an effective tool to enhance the determination of crystal structures and defects in high-resolution electron microscopy. The essence is to transform a single image that does not intuitively represent the examined crystal structure into the structure image. The principle and method of image deconvolution together with the related image contrast theory, the pseudo weak phase object approximation (pseudo WPOA), are briefly described. The method has been applied to different types of dislocations, twin boundaries, stacking faults, and one-dimensional incommensurate modulated structures. Results on the semiconducting epilayers Si0.76Ge0.24/Si and 3C-SiC/Si are given in some detail. The results on other compounds including AlSb/GaAs, GaN, Y0.6Na0.4Ba2Cu2.7Zn0.3O7-δ, Ca0.28Ba0.72Nb2O6 and Bi2.31Sr1.69CuO6+δ are briefly summarized. It is also shown how to recognize atoms of Si from C based on the pseudo WPOA, when the defect structures in SiC was determined at the atomic level with a 200 kV LaB6 microscope.

Structure determination of a new polymorph of TiO2 by high-resolution electron microscopy and computer simulations

1989 ◽  
Vol 47 ◽  
pp. 416-417
Author(s):  
Jillian F. Banfield ◽  
David R. Veblen ◽  
David J. Smith
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Electron Diffraction ◽  
Computer Simulations ◽  
High Resolution Electron Microscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Naturally Occurring ◽  
Resolution Electron

A new, naturally occurring polymorph of TiO2 has been identified. This mineral forms lamellae generally only a few nanometers wide in anatase from two localities near Bintal Valais, Switzerland. The abundance of this mineral in anatase is too low to allow investigation by X-ray diffraction. The unit cell determined by electron diffraction is triclinic, with a = 0.754 nm, b = 0.448 nm, c = 0.616 nm, α = 78.90°, β = 124.55°, γ = 96.54°. The coherently intergrown lamellae are oriented with b parallel to a of anatase; the interface is parallel to (103) anatase.

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