Neutron Scattering

Fig . 18 .12 : Examples of crystallographic
planes (top) and their
accessory pole figures (bottom)
for a two-dimensional (a) and a
three-dimensional (b) single
crystal with one fzxed pole per
plane and for a polycrystalline
sample (c and d) with a scatter of
poles;
(a) (001)plane and its counterpart
(00-1) (north-south
normal directions)
(b) cubic Basis planes (100),
(010), (001) (left) and Body
diagonal planes {111} (right)
(c)
spread ofdierently oriented
(001) planes
(d) spread ofdierently oriented
cubic Basis planes {1001
4 .2 Experimental Pole figures
An experimental (hkl) pole figure is obtained by diffraction methods by measuring the
intensity of a Bragg reflection (hkl) for a variety of différent sample orientations . Usually, at
least so far, one uses monochromatic neutrons (or X-rays) . The simplest instrumental setup is
that of a four-circle diffractometer equipped with a Eulerian cradle (cp, x rotation axes) as
sample goniometer (Fig . 18 .13) and a simple counting tube, i .e . an instrument as used for
single crystal structure investigations . A stationaiy detector is positioned in thé peak
maximum ofa reflection, and sample orientation dependent measurements are performed, e .g .
in a step scanning mode, realizing an equal area pole figure grid (Fig . 18 .13) .
Fig. 18 .13 : Eulerian cradle with rotation axes (p ,- (w = 20/2 position) (left) and typical
(c5ß) - polefigure scanning grid (right)
18- 8