Figure 7
(a) Gypsum unit cell with four selected crystal planes labelled; the fibre axis is parallel to the a axis direction. (b) Gypsum reciprocal space with labelled reciprocal spots corresponding to the planes in (a). (c) All reciprocal space spots in (b) spun around the fibre axis, then cut by the scattering vector plane (B, also parallel to the goniometer axis) of a symmetric 2D scan. All the measured reciprocal spots form parallel intersection lines which are perpendicular to the fibre axis. Measuring the reciprocal plane A perpendicular to the fibre axis [Fig. 3(b)] allows us to determine the crystallographic orientation of the fibre axis. |