Optical, dielectric and electroconvection studies of a five-ring ester-difluoromethoxy linked ferroelectric nematic...

There has been a surge of interest in the synthesis and characterisation of new ferroelectric nematic liquid crystals in recent times, focussing on understanding and optimising their properties for fundamental and practical applications. Here, we report experimental studies of a five-ring ester-difluoromethoxy linked ferroelectric nematic liquid crystal with a lateral methoxy group. We measure temperature-dependent electric polarisation, investigate the critical behaviour of the birefringence across the nematic to ferroelectric nematic phase transition and discuss the dielectric properties in view of the two physical models proposed recently. We study electrohydrodynamic instability and show that the phase diagram above the N-N_F transition in the voltage-frequency plane is much richer than the N_F phase.