Phase Transition and Structure Studies of a Liquid Crystalline Schiff-Base Compound (4O.8)

Abstract

Calorimetric and X-ray powder diffraction studies of N-(4-n-butyloxybenzylidene)-4′-n′-octylaniline are presented. Heat capacity measurements have been performed by adiabatic calorimetry in the temperature range from 5 K to 375 K. Three liquid crystalline phases, i.e., nematic, smectic A and smectic B, and an ordered crystal of triclinic structure and two new metastable crystal phases were observed. In addition, the crystalline smectic B phase of different sequence of molecular layers than liquid crystalline smectic B, has been found. Both smectic B phases have been vitrified. For the smectic B phase a hexagonal unit cell has been identified by X-ray diffraction. The diffraction pattern of glass of crystalline smectic B phase is shown.

Keywords:

• Heat capacity
• liquid crystal
• phase transitions
• X-ray diffraction

Acknowledgment

We thank M.Sc. Hal Suzuki to help us with calculation of the thermodynamic functions. One of the authors (E.J.) would like to thank the Research Center for Structural Thermodynamics for a great hospitality during the scholarship.

Notes

^#Contribution No. 12 from the Research Center for Structural Thermodynamics.