| | |
Summary: © 1999 Macmillan Magazines Ltd
such as dislocations, and the X-ray scattering
from such defects is greater than the scatter-
ing from bonding electrons. But using an
electronmicroscopeitispossibletoimagethe
crystal,selectaperfectregionbetweencrystal
defects, and form a diffraction pattern from
this perfect region. Zuo et al.1
use an electron
beam focused to nanometre dimensions to
find a region of the crystal where the perfect-
crystal theory of diffraction applies. They
also filtered the electrons transmitted by the
specimen to remove inelastically scattered
electrons and ease comparison with theory.
Using these methods, very accurate charge-
density maps can be made which reveal the
shapeoftheelectronbonds.
In metal oxides, the metal ions interact
mainly with the oxygen atoms. But in many
|
