Ferroelastic Phase Transition and Domain Structure in Urea Inclusion Compounds with Two Different Guest Families: N-Alkanes and alpha, omega-Dicarboxylic Acids

摘要

The ferroelastic phase transitions and the domain structure of n-alkane/urea (n-heptadecane/ urea, n-nonadecane/urea) and alpha, omega-dicarboxylic acid/urea (1,6-hexanedicarboxylic acid (suberic acid)/urea, 1,8-octanedicarboxylic acid (sebacic acid)/urea and 1, 10-decanedicarboxylic acid/urea) crystals has been investigated. The ferroelastic character of the domain structure was analysed by applying an external uniaxial stress on the twinned crystals. In the case of the n-alkane/urea crystals the switching process and the ferroelastic domain distribution correspond to the phase transition 622F222 suggested in the literature. alpha, omega-dicarboxylic acid/urea crystals can be classified as hard ferroelastic. The domain structure distribution of these crystal can be explained by a orthorhombic to triclinic phase transition.