Phase transformation and defect structures in thin-film TaSi2 produced by co-sputtering were investigated as a function of annealing temperature by transmission electron microscopy. Crystallization of amorphous TaSi2 thin films occurred at 400C without forming any metastable phases. Most of C40 TaSi2 crystallites contain planar faults parallel to (00▪1) basal planes. Convergent-beam electron diffraction indicated that these planar faults were not simple stacking faults but were twin boundaries bounded by two adjacent enantiomorphically-related twin domains; i.e., domains belonging to the space groups P6222 (right-handed) and P6422 (left-handed) having the identical crystal orientation arrange alternatively separated by twin boundaries parallel to (00▪1). The formation of these enantiomorphically-related domains in TaSi2 thin films with the hexagonal C40 structures was discussed in comparison with the formation of twin-related domains in MoSi2 (the tetragonal C11b structure) and TiSi2 (the orthorhombic C54 structure) thin films. A new convergent-beam electron diffraction method was proposed for identification of enantiomorphically-related crystals, in which asymmetry in the intensity of Bijvoet pairs of FOLZ disks in an experimental symmetrical zone-axis convergent-beam electron diffraction pattern was compared with that in a computer simulated convergent-beam electron diffraction pattern.

Defect Structures in TaSi2 Thin Films Produced by Co-Sputtering. H.Inui, A.Fujii, T.Hashimoto, K.Tanaka, M.Yamaguchi, K.Ishizuka: Acta Materialia, 2003, 51[8], 2285-96