Defects in [1, 6-DI(N-Carbazolyl)-2, 4-Hexadiyne] Diacetylene Crystals

Abstract

ABSTRACTThe effect of solution concentration on the morphology of [l, 6-di(N-carbazolyl)-2, 4-hexadiyne] (DCHD) diacetylene crystals has been studied by conventional TEM, SAED, and HREM. Crystals obtained by evaporating 0.1 wt% DCHD-chloroform solution on amorphous carbon films are fibrous (about 3 μm wide and 100 μm long) and have defects such as kinks, pores, cracks, and dislocations. Two characteristic single crystal textured morphologies are found in these crystals: (1) a microfibrillar structure consisting of highly-oriented crystallites, with greater axial sizes than lateral sizes, slightly misorienting with a standard deviation of 3°; and (2) a“cross-hatched”structure consisting of highly-oriented crystalline domains separated by two groups of obliquely oriented boundary planes which make (45+/-3)∘ and (37+/-3)∘ angles respectively with the [001] chain direction. Crystals obtained by evaporating more dilute (0.01 wt%) DCHD-chloroform solutions onto amorphous carbon films are about 0.1–0.2 μm long and 0.05–0.1 μm wide and have the chain axis oriented perpendicular to the carbon support film. For these crystals, lateral-chain-invariant (LCI) small angle grain boundaries have been found in HREM images of the [001] zone axis.