96
center of the pattern. If a lattice parameter measurement
is to be made using the relative voltage differences
required to go from one three line point intersection to
another three line point intersection, this measurement
cannot be accurate if any noncubicity is present. Braski
alluded to the nonacceptability of using the B = (^11*0
patterns for his measurements because of the sensitivity
of this pattern for noncubic effects. All patterns are
sensitive to strain effects.
There should be other CBED zone axis patterns that
could be used to make the measurements for which the B =
<.114> pattern was used in this study. The B = <.100>
pattern would be the most crystallographically sensible.
There is no gamma/gamma prime overlap along this
direction.
Using equation (1), it is simple to calculate the
expected HOLZ for B = ^001^.
At 100 kV:
R = 27.07,
aG = 3.56 Angstroms,
B = <001>,
gB = 1, and
h2+k2+l2 = 193.
The Bragg angle for this F0LZ ring is about 4.2 degrees at
100 kV. This means the F0LZ will be 8.4 degrees from the
center of the pattern, far from the transmitted spot and