Dielectric response of a ferroelectric nematic liquid crystalline phase in thin cells

Vaupotič, Nataša; Pociecha, Damian; Rybak, Paulina; Matraszek, Joanna; Čepič, Mojca; Wolska, Joanna M.; Górecka, Ewa

doi:10.1080/02678292.2023.2180099

Cited by 14 publications

(5 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This behaviour agrees well with that reported for other ferroelectric nematogens; [6,8,11,14,15,20] the strong dielectric mode might be attributed to the collective movement of the polarization direction, phason mode. [36] The polar character of the N F phase was also confirmed by the observation of electric switching. Thus, when an AC voltage was applied to the cell, a single current peak per half cycle was registered and this is associated with the reversal of the spontaneous electric polarization, Chemistry-A European Journal Figure 7.…”

Section: Resultsmentioning

confidence: 77%

Molecular Shape, Electronic Factors, and the Ferroelectric Nematic Phase: Investigating the Impact of Structural Modifications

Cruickshank

Pociecha

Górecka

et al. 2023

Chemistry A European J

Self Cite

View full text Add to dashboard Cite

The synthesis and characterisation of two series of low molar mass mesogens, the (4-nitrophenyl) 2-alkoxy-4-(4methoxybenzoyl)oxybenzoates (NT3.m) and the (3-fluoro-4nitrophenyl)2-alkoxy-4-(4-methoxybenzoyl)oxybenzoates (NT3F.m), are reported in order to investigate the effect of changing the position of a lateral alkoxy chain from the methoxy-substituted terminal ring to the central phenyl ring in these two series of materials based on RM734. All members of the NT3.m series exhibited a conventional nematic phase, N, which preceded the ferroelectric nematic phase, N F , whereas all the members of the NT3F.m series exhibited direct N F -I transitions except for NT3F.1 which also exhibited an N phase. These materials cannot be described as wedgeshaped, yet their values of the ferroelectric nematic-nematic transition temperature, T N F N , exceed those of the corresponding materials with the lateral alkoxy chain located on the methoxy-substituted terminal ring. In part, this may be attributed to the effect that changing the position of the lateral alkoxy chain has on the electronic properties of these materials, specifically on the electron density associated with the methoxy-substituted terminal aromatic ring. The value of T NI decreased with the addition of a fluorine atom ortho to the nitro group in NT3F.1, however, the opposite behaviour was found when the transition temperatures of the N F phase were compared which are higher for the NT3F.m series. This may reflect a change in the polarity and polarizability of the NT3F.m series compared to the NT3.m series. Therefore, it is suggested that, rather than simply promoting a tapered shape, the role of the lateral chain in inhibiting anti-parallel associations and its effect on the electronic properties of the molecules are the key factors in driving the formation of the N F phase.

show abstract

Section: Resultsmentioning

confidence: 77%

Molecular Shape, Electronic Factors, and the Ferroelectric Nematic Phase: Investigating the Impact of Structural Modifications

Cruickshank

Pociecha

Górecka

et al. 2023

Chemistry A European J

Self Cite

View full text Add to dashboard Cite

show abstract

“…The high fluidity of the N F phase combined with its polar properties immediately caught the attention of scientists around the world due to not only its huge application potential but also its fundamental significance as a spontaneously ferroelectric fluid. The N F phase became one of the hottest topics in liquid crystal research. − Owing to the fluid nature of the N F phase, a uniform polarization direction can be obtained in large areasa key to realizing its application potential . However, the question arises whether the competitive interactions that drive the formation of the N F phase can also lead to other complex structures as is the case with the improper ferroelectric liquid crystal phases.…”

Section: Introductionmentioning

confidence: 99%

To Be or Not To Be Polar: The Ferroelectric and Antiferroelectric Nematic Phases

Cruickshank,

Rybak,

Majewska

et al. 2023

ACS Omega

Self Cite

View full text Add to dashboard Cite

We report two new series of compounds that show the ferroelectric nematic, NF, phase in which the terminal chain length is varied. The longer the terminal chain, the weaker the dipole–dipole interactions of the molecules are along the director and thus the lower the temperature at which the axially polar NF phase is formed. For homologues of intermediate chain lengths, between the non-polar and ferroelectric nematic phases, a wide temperature range nematic phase emerges with antiferroelectric character. The size of the antiparallel ferroelectric domains critically increases upon transition to the NF phase. In dielectric studies, both collective (“ferroelectric”) and non-collective fluctuations are present, and the “ferroelectric” mode softens weakly at the N–NX phase transition because the polar order in this phase is weak. The transition to the NF phase is characterized by a much stronger lowering of the mode relaxation frequency and an increase in its strength, and a typical critical behavior is observed.

show abstract

“…Indeed, these include some which mean that the phase may have real application potential. Some of these properties include: being easy to align; [9,10] having a strong non-linear optical response; [11][12][13][14][15] high polarisation values; [7,8,16,17] large dielectric permittivity [18][19][20][21][22][23][24][25][26] (although there has been some debate around the exact magnitude of these permittivity values) [26,27] and switching occurs for very low electric fields. [7,8,20,[28][29][30][31][32][33] While there has been a large upsurge in materials in the last couple of years that have been reported to exhibit the ferroelectric nematic phase, the majority of these compounds fall into a relatively small structure space.…”

Section: Introductionmentioning

confidence: 99%

“…Indeed, these include some which mean that the phase may have real application potential. Some of these properties include: being easy to align; [9,10] having a strong non‐linear optical response; [11–15] high polarisation values; [7,8,16,17] large dielectric permittivity [18–26] (although there has been some debate around the exact magnitude of these permittivity values) [26,27] and switching occurs for very low electric fields [7,8,20,28–33] …”

Section: Introductionmentioning

confidence: 99%

The Emergence of a Polar Nematic Phase: A Chemist's Insight into the Ferroelectric Nematic Phase

Cruickshank

2024

ChemPlusChem

View full text Add to dashboard Cite

The discovery of a new polar nematic phase; the ferroelectric nematic, has generated a great deal of excitement in the field of liquid crystals. To date there have been around 150 materials exhibiting the ferroelectric nematic phase, in general following three key archetypal structures with these compounds known as RM734, DIO and UUQU‐4N. In this review, the relationship between the molecular structure and the stability of the ferroelectric nematic, NF, phase will be described from a chemist’s perspective. This will look to highlight the wide variety of functionalities which have been incorporated into these archetypal structures and how these changes influence the transition temperatures of the mesophases present. The NF phase appears to be stabilised particularly by reducing the length of terminal alkyl chains present and adding fluorines laterally along the length of the molecular backbone. This review will look to introduce the background of the ferroelectric nematic phase before then showing the molecular structures of a range of materials which exhibit the phase, describing their structure‐property relationships and therefore giving an up‐to‐date account of the literature for this fascinating new mesophase.

show abstract

Dielectric response of a ferroelectric nematic liquid crystalline phase in thin cells

Cited by 14 publications

References 20 publications

Molecular Shape, Electronic Factors, and the Ferroelectric Nematic Phase: Investigating the Impact of Structural Modifications

Molecular Shape, Electronic Factors, and the Ferroelectric Nematic Phase: Investigating the Impact of Structural Modifications

To Be or Not To Be Polar: The Ferroelectric and Antiferroelectric Nematic Phases

The Emergence of a Polar Nematic Phase: A Chemist's Insight into the Ferroelectric Nematic Phase

Contact Info

Product

Resources

About