Nanoscopic crystallography of chalcopyrite CuInS2 by techniques of convergent-beam electron diffraction

We investigate the crystallography of CuInS2 single crystals on a nanoscopi c scale in space by transmission electron microscopy. We combine several co nvergent-beam electron diffraction techniques (CBED). Microdiffraction, a v ariant of CBED with a moderate convergent beam, is used for a space-group a nalysis. The arrangements of so-called defect and excess lines as visible i n (000) and high-order Laue zone CBED discs are utilized for the determinat ion of the lattice parameters and for the exact atom positions within the c rystallographic unit cell respectively. Therefore the experimental CBED pat terns are compared with simulations based on the dynamical diffraction theo ry. These investigations reveal the analysed CuInS2 material to be a reliab le model substance for chalcopyrites (contrary to CuInSe2). We utilize this model substance to determine reflections that occur owing to 'Umweganregun gen'. The unambiguous identification of such reflections is indispensable f or the differentiation between chalcopyrites and related crystal structures .