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Figure 16.9: Three cubic unit
cells and the corresponding
lattices.
The closet packing
arrangement of uniform spheres.
When spheres are closest packed so that the spheres
in the third layer are directlly over those in the first layer
(aba) the unit cell is hexagonal prism illustrated here in red
A toy slide puzzle
A section of a surface containing
copper atoms (red) and an indium
atom (yellow).
When spheres are packed in the abc
arrangement, the unit cell is face-center cubic.
Figure 16.16:
The indicated
sphere has
12 equivalent
nearest
neighbors.
The net number of spheres
in a face-centered cubic unit cell.
Volume
of a unit
cell
(2r, 4r, r)
In the body-centered cubic unit cell the
spheres touch along the body diagonal.
Simple Cubic Cell
On the face of the
body-centered cubic unit cell.
The relationship of the body
diagonal (b) to the face diagonal (f) and the edge
(e) for the body-centered cubic unit cell.
Structure of NaCl: an ionic crystal
Sodium chloride
crystals are brittle
Why 6-coordinated ?
The locations (gray x) of the octahedral holes
in the face-centered cubic unit cell.
The octahedral hole (shown in yellow)
lies at the center of six spheres that touch
along the edge of the square
(a) A simple cubic array with X- ions,
with an M+ ion in the center (in the cubic hole)
(b) The body diagonal b equals
Figure 16.36:
The holes
that exist
among
closest
packed
uniform
spheres
16.38: (a)
The
tetrahedral
hole
(b) The
center of
the
tetrahedral
hole
One packed sphere and its relationship to the
tetrahedral hole
(a) The location (x) of a tetrahedral hole
in the face-centered cubic unit cell.(b) one of
the tetrahedral (c) the unit cell (d) The
alternate tetrahedral
Figure 16.43: Defects in
crystalline
ionic solids
Figure 16.22:
The electron
sea model
for
metals
postulates a
regular array
of cations
in a "sea" of
valence
electrons.
Grains of nanophase palladium
magnified 200,000 times by an
electron microscope.
Source: Nanophase Technologies Corporation