A synchrotron white-beam X-ray Laue study was made of thin epitaxial films, of icosohedral material, which were prepared by chemical vapor deposition at 1300C onto 6H-SiC (00▪1) (on-axis) substrates. The epitaxial relationship was (111)<10¯1>||(00▪1)<11▪0>, and double-positioning twins were present. Diffractometry showed that the 2 twinning variants existed in the ratio of 2:1. A reciprocal space map of the epilayer revealed a single peak (12arcmin wide in the ω scan direction and 1.6arcmin wide in the θ-2θ scan direction) and high degrees of both tilt and strain broadening. Cross-sectional transmission electron micrographs exhibited twin domains, with one twin orientation appearing as a matrix; holding grains (between 0.2 and 4μm wide) of the second twin orientation. A high density of dislocations was also found.

Double-Positioning Twinning in Icosahedral B12As2 Thin Films Grown by Chemical Vapor Deposition. W.M.Vetter, R.Nagarajan, J.H.Edgar, M.Dudley: Materials Letters, 2004, 58[7-8], 1331-5