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Two mechanisms for the formation of ferronematic phase in DIO as studied by dielectric spectroscopy

DOI: 10.1016/j.molliq.2023.121570 DOI Help

Authors: Neelam Yadav (Trinity College, The University of Dublin) , Yuri P. Panarin (Trinity College, The University of Dublin; TU Dublin) , Jagdish K. Vij (Trinity College, The University of Dublin) , Wanhe Jiang (University of Hull) , Georg H. Mehl (University of Hull)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of Molecular Liquids , VOL 6

State: Published (Approved)
Published: March 2023
Diamond Proposal Number(s): 31552

Open Access Open Access

Abstract: A non-chiral ferroelectric nematic compound with a 1,3-dioxane unit in the mesogenic core called 2,3',4',5'-tetrafluoro-[1,1'-biphenyl]-4-yl 2,6-difluoro-4-(5-propyl-1,3-dioxan-2-yl) benzoate (DIO) was studied by dielectric spectroscopy in the frequency range 0.1 Hz to 10 MHz over a wide range of temperatures. The compound exhibits three nematic phases on cooling from the isotropic phase, i.e., the ordinary paraelectric nematic N; the intermediate nematic NX and the ferroelectric NF phases. The least frequency process is due to the dynamics of ions. The middle frequency relaxation process P1 is like as observed in other ferronematic compounds and this mode is a continuation of the molecular flip-flop motion in the isotropic phase to the collective dynamics of dipoles which are strongly coupled with the splay fluctuations in nematic phases. In addition to this process, DIO shows an additional collective relaxation process P2 at higher frequencies both in the N and the NX phases. This mode originates from the polar/chiral molecules of the opposite chirality, these arise from the spontaneous symmetry breaking of achiral mesogens in the N phase. Both collective processes, P1 and P2, show soft mode-like characteristic behavior on cooling from the N to the NX-NF phase transition temperature and are shown to contribute independently to the formation of the ferronematic NF phase.

Subject Areas: Chemistry, Materials

Instruments: B23-Circular Dichroism

Added On: 15/03/2023 11:00


Discipline Tags:

Physical Chemistry Chemistry Materials Science

Technical Tags:

Spectroscopy Circular Dichroism (CD)