J. Phys. I France
Volume 6, Numéro 12, December 1996
Page(s) 1575 - 1580
DOI: 10.1051/jp1:1996175
J. Phys. I France 6 (1996) 1575-1580

Twist Morphology of Organic Crystal (BPE-DMB)IBr $\mathsf{_2}$

Kazushige Kawabata1, Tomonori Kumagai1, Makoto Mizutani2 and Takashi Sambongi1

1  Department of Physics, Graduate School of Science, Hokkaido University, Sapporo 060, Japan
2  PRESTO, JRDC (Idemitsu Kosan Co. LTD), Sodegaura Chiba 299-02, Japan

(Received 26 April 1996, accepted 1 July 1996)

Crystals of (BPE-DMB)IBr 2, where BPE-DMB denotes 1,4-bis[2-(pyrene-1-yl) vinyl]-2,5-dimethylbenzene, are found to be twisted along the growing axis. Their morphology was examined in detail by X-ray examination, scanning electron and optical microscopic observations. It was found that the twisted crystals are quasi-stable and that the twisting is not discrete but rather continuous in sub-micron scale. The relation between a twist pitch and the cross-section area was obtained and compared with the dislocation model proposed by Eshelby.

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