Highly ordered hexatic phases with large spontaneous polarization

Abstract

In this article the physical properties of hexatic phases of three substances MHPNBC, FOOPP and FNHPP have been studied by differential scanning calorimetry, texture observation and dielectric spectroscopy. Experimental results are discussed from the point of view of existing theories. It is interesting that two of the substances studied, the FOOPP and FNHPP, exhibit enhanced spontaneous polarization in the highly ordered SmI* phase and show a jump of the spontaneous polarization in the vicinity of the SmC*–SmI* transition. In the SmI* phase of FOOPP a very high value of spontaneous polarization of the order of 530 nC cm⁻² was found. Based on the results obtained the macroscopic and microscopic properties of the hexatic phases are discussed.

Keywords:

• Hexatic phase
• Spontaneous polarization
• Bond orientational order
• Phase transitions

Acknowledgments

Three of us (S.W., A.M. and M.M.) would like to thank the State Committee for Scientific Research (KBN) for financial support in scope of the grant No. 1 P03B 056 28.