Dielectric spectroscopy and electrical conductivity measurements on high-tilted antiferroelectric materials

ABSTRACT

Dielectric spectroscopic measurements have been reported on three synthesized pure liquid crystalline compounds having paraelectric (SmA*), ferroelectric (SmC*) and antiferroelectric (SmC_A*) phases in the frequency range of 40 Hz–25 MHz. Several relaxation modes i.e. low-frequency P_L Mode and high-frequency P_H Mode in the SmC_A* phase, Goldstone Mode (GM) in SmC* phase and Soft Mode (SM) in SmA* phase have been observed. These materials with wide antiferroelectric range are found to possess low relaxation times, thus making them promising materials for applications. The Cole–Cole plot shows the modes in the SmC_A* phase to be much weaker than in the SmC* phase. Dielectric loss is maximum in SmC* phase due to the Goldstone Mode. Additionally, the AC electrical conductivity is found to be maximum in the SmC* phase and is dependent on the frequency. Maximum DC conductivity of these materials is of the order of 10⁻⁵ Ohm⁻¹ m⁻¹.

KEYWORDS:

• Antiferroelectric liquid crystals
• dielectric spectroscopy
• relaxation time
• dielectric strength
• AC conductivity
• activation energy

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Department of Science and Technology, New Delhi [grant numbers EMR/2016/005001; EEQ/2017/000829].