Electro-optic study of the phase behavior of mixtures of two ferroelectric nematic liquid crystals

We have shown previously that the second nematic phase (N_F) of the thermotropic liquid crystal RM374 is ferroelectric [1]. We have also recently confirmed ferroelectricity in DIO, a nematic previously reported to be ferroelectric-like [2]. Here we study the phase behavior, miscibility, and electro-optics of binary mixtures of RM734 and DIO. As reported in the literature, the N_F phase of RM734 ranges from 133°C to 70°C and the N_F phase of DIO from 68.8°C to 34°C. As expected, the N_F temperature range in the mixtures is extended to lower temperatures, with field-induced molecular reorientation in response to a 10 V/mm, in-plane applied field observed at temperatures as low as 28°C in a 50:50 mixture. The temperature range of the phase between the N and N_F phases in DIO is reduced in the mixtures and disappears at higher RM734 concentration.
[1] “First-Principles Demonstration of Ferroelectricity in a Thermotropic Nematic Liquid Crystal: Spontaneous Polar Domain Formation and Spectacular Electro-Optics”, X. Chen et al. PNAS 2020.
[2] “A Fluid Liquid-Crystal Material with Highly Polar Order”, H. Nishikawa et al. AdvMat 2017.
Author for Correspondence: noel.clark@colorado.edu