Investigations on noncubic crystals with the divergent X-ray beam technique

The divergent X-ray beam technique is very useful for the study of small monocrystalline sample regions. The diffraction patterns are cone-shaped. The size of the cone angle and the direction of the cone axis depend form the lattice parameters and the orientation of the investigated crystal. An appropriate evaluation permits the simple determination of lattice parameters, even of those of noncubic crystals and the determination of crystal orientation. The comparison of X-ray divergent beam patterns of different regions of the sample makes it possible to discover changes in the imperfect crystal structure such as local lattice parameter variations, disorientations, and twinnings in regions up to 10 μm in diameter. Suitable methods for utilization will be shown here.