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Nacke P, Tuffin R, Klasen-Memmer M, Rudquist P, Giesselmann F. Revealing the antipolar order in the antiferroelectric SmZ A phase by means of circular alignment. Sci Rep 2024; 14:15018. [PMID: 38951542 PMCID: PMC11217385 DOI: 10.1038/s41598-024-65275-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Accepted: 06/18/2024] [Indexed: 07/03/2024] Open
Abstract
Many ferroelectric nematic liquid crystals, like one of the archetype materials, DIO, do not have a direct paraelectric N to ferroelectric NF phase transition, but exhibit yet another phase between N and NF. This phase has recently been proposed to be antiferroelectric, with a layered structure of alternating polarization normal to the average director and is sometimes referred to as Smectic ZA (SmZA). We have examined the SmZA phase in circularly rubbed (CR) cells, known to discriminate between the polar NF and the non-polar N phase from the configuration of disclination lines formed. We find that the ground state of SmZA has the same disclination configuration as the non-polar N phase, demonstrating that the SmZA phase is also non-polar, i.e., it has no net ferroelectric polarization. At the same time, the SmZA texture generally has a grainy appearance, which we suggest is partly a result of the frustration related to layered order combined with the imposed twist in CR cells. We discuss possible orientations of the smectic layers, depending on the alignment conditions. While a horizontal SmZA layer structure is always compatible with surface-induced twist, a vertical layer structure would tend to break up in a twisted bookshelf structure to match non-parallel alignment directions at the two surfaces.
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Affiliation(s)
- Pierre Nacke
- Institute of Physical Chemistry, University of Stuttgart, 70569, Stuttgart, Germany
| | - Rachel Tuffin
- Display Solutions, Merck Electronics KGaA, 64293, Darmstadt, Germany
| | | | - Per Rudquist
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 41296, Gothenburg, Sweden.
| | - Frank Giesselmann
- Institute of Physical Chemistry, University of Stuttgart, 70569, Stuttgart, Germany.
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2
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Marni S, Caimi F, Barboza R, Clark N, Bellini T, Lucchetti L. Fluid jets and polar domains, on the relationship between electromechanical instability and topology in ferroelectric nematic liquid crystal droplets. SOFT MATTER 2024; 20:4878-4885. [PMID: 38819946 DOI: 10.1039/d4sm00317a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2024]
Abstract
Ferroelectric nematic liquid crystals are a class of recently discovered fluid materials formed by highly polar molecules that spontaneously align along a common direction, giving rise to a macroscopic polarization P. Since the polarization vector is locally collinear to the optical axis n, the study of the spatial patterns of n enables deducing the structure of P. We have carried on such topological study on ferroelectric nematic droplets confined between two solid ferroelectric substrates both when the droplet is in equilibrium and during a jet-emission phase that takes place when the solid surfaces become sufficiently charged. We find that in equilibrium the droplet splits in striped domains in which P has alternating directions. When these domains extend close to the droplets' perimeter, P adopts a π-twisted structure to minimize accumulation of polarization charges. As the substrate surface charge is increased above threshold, fluid jets are emitted with a quasi-periodic pattern, a behaviour suggesting that their location is governed by an electrofluidic instability on the droplets' rim, in turn indicating the absence of specific trigger points. Soon after their emission, the jet periodicity is lost; some jets retract while other markedly grow. In this second regime, jets that grow are those that more easily connect to polar domains with P along the jet axis. Occasionally, ejection of isolated spikes also occurs, revealing locations where polarization charges have accumulated because of topological patterns extending on length scales smaller than the typical domain size.
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Affiliation(s)
- Stefano Marni
- Dipartimento SIMAU, Università Politecnica delle Marche, via Brecce Bianche, Ancona 60131, Italy.
| | - Federico Caimi
- Medical Biotechnology and Translational Medicine Dept., University of Milano, Segrate 20054, Italy.
| | - Raouf Barboza
- Dipartimento SIMAU, Università Politecnica delle Marche, via Brecce Bianche, Ancona 60131, Italy.
| | - Noel Clark
- Department of Physics, Soft Materials Research Center, University of Colorado, Boulder, CO, 80305, USA
| | - Tommaso Bellini
- Medical Biotechnology and Translational Medicine Dept., University of Milano, Segrate 20054, Italy.
| | - Liana Lucchetti
- Dipartimento SIMAU, Università Politecnica delle Marche, via Brecce Bianche, Ancona 60131, Italy.
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3
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Zou Y, Aya S. Extended free-energy functionals for achiral and chiral ferroelectric nematic liquid crystals: theory and simulation. Phys Chem Chem Phys 2024; 26:15637-15647. [PMID: 38764421 DOI: 10.1039/d4cp00449c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/21/2024]
Abstract
Polar nematic liquid crystals are new classes of condensed-matter states, where the inversion symmetry common to the traditional apolar nematics is broken. Establishing theoretical descriptions for the novel phase states is an urgent task. Here, we develop a Landau-type mean-field theory for both the achiral and chiral ferroelectric nematics. In the polar nematic states, the inversion symmetry breaking adds three new contributions: an additional odd elastic term (corresponding to the flexoelectricity in symmetry) to the standard Oseen-Frank free energy, electrostatic effect and an additional Landau term relating to the gradient of local polarization. The coupling between the scalar order parameter and polarization order should be considered. In the chiral and polar nematic state, we reveal that the competition between the twist elasticity and polarity dictates effective compressive energy arising from the quasi-layer structure. The polarization gradient is an essential term for describing the ferroelectric nature. Besides, we successfully simulate an experimentally reported structural transition in ferroelectric nematic droplets from a concentric-vortex-like to a line-disclination-mediated topology based on the developed theory. The approaches provide theoretical foundations for testing and predicting polar structures in emerging polar liquid crystals.
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Affiliation(s)
- Yu Zou
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China.
- Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou 510640, China
| | - Satoshi Aya
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China.
- Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou 510640, China
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4
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Yang M, Guo M, Xu E, Ren W, Wang D, Li S, Zhang S, Nan CW, Shen Y. Polymer nanocomposite dielectrics for capacitive energy storage. NATURE NANOTECHNOLOGY 2024; 19:588-603. [PMID: 38172431 DOI: 10.1038/s41565-023-01541-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 10/10/2023] [Indexed: 01/05/2024]
Abstract
Owing to their excellent discharged energy density over a broad temperature range, polymer nanocomposites offer immense potential as dielectric materials in advanced electrical and electronic systems, such as intelligent electric vehicles, smart grids and renewable energy generation. In recent years, various nanoscale approaches have been developed to induce appreciable enhancement in discharged energy density. In this Review, we discuss the state-of-the-art polymer nanocomposites with improved energy density from three key aspects: dipole activity, breakdown resistance and heat tolerance. We also describe the physical properties of polymer nanocomposite interfaces, showing how the electrical, mechanical and thermal characteristics impact energy storage performances and how they are interrelated. Further, we discuss multi-level nanotechnologies including monomer design, crosslinking, polymer blending, nanofiller incorporation and multilayer fabrication. We conclude by presenting the current challenges and future opportunities in this field.
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Affiliation(s)
- Minzheng Yang
- School of Materials Science and Engineering, State Key Lab of New Ceramics and Fine Processing, Tsinghua University, Beijing, China
| | - Mengfan Guo
- School of Materials Science and Engineering, State Key Lab of New Ceramics and Fine Processing, Tsinghua University, Beijing, China
| | - Erxiang Xu
- School of Materials Science and Engineering, State Key Lab of New Ceramics and Fine Processing, Tsinghua University, Beijing, China
| | - Weibin Ren
- School of Materials Science and Engineering, State Key Lab of New Ceramics and Fine Processing, Tsinghua University, Beijing, China
| | - Danyang Wang
- School of Materials Science and Engineering, The University of New South Wales, Sydney, Australia
| | - Sean Li
- School of Materials Science and Engineering, The University of New South Wales, Sydney, Australia
| | - Shujun Zhang
- Institute for Superconducting and Electronic Materials, AIIM, University of Wollongong, Wollongong, Australia.
| | - Ce-Wen Nan
- School of Materials Science and Engineering, State Key Lab of New Ceramics and Fine Processing, Tsinghua University, Beijing, China.
| | - Yang Shen
- School of Materials Science and Engineering, State Key Lab of New Ceramics and Fine Processing, Tsinghua University, Beijing, China.
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5
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Zou Y, Yang J, Zhang X, Huang M, Aya S. Topology of ferroelectric nematic droplets: the case driven by flexoelectricity or depolarization field. SOFT MATTER 2024; 20:3392-3400. [PMID: 38619075 DOI: 10.1039/d3sm01042b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
The recent discovery of ferroelectric nematics provides new opportunities for exploring polar topology in liquid matter. Here, we report numerous potential polarization topological states (e.g., polar vortex-like and line disclination mediated structures) in confined ferroelectric nematics with similar free-energy levels. In the experiment, they appear according to the confinement size and surface anchoring conditions. Based on a minimal analytical approach, we reveal that the topological transformation is balanced among the nematic elasticity, the polarization gradient, the flexoelectric and the depolarization interactions.
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Affiliation(s)
- Yu Zou
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou, 510640, P. R. China.
| | - Jidan Yang
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou, 510640, P. R. China.
| | - Xinxin Zhang
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou, 510640, P. R. China.
| | - Mingjun Huang
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou, 510640, P. R. China.
- Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou, 510640, P. R. China
| | - Satoshi Aya
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou, 510640, P. R. China.
- Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou, 510640, P. R. China
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6
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Aya S, Xu H, Long H, Yiliu M, Zou Y, Huang M. Response of helielectric nematics under an in-plane electric field. Phys Chem Chem Phys 2024; 26:12422-12432. [PMID: 38619386 DOI: 10.1039/d4cp00588k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
In traditional chiral nematic liquid crystals, the apolar cholesterics, the dielectric effect is the main driving force for responding to an electric field. The emerging polar chiral nematics, dubbed helielectric nematics, are the polar counterparts of the cholesterics. The head-to-tail symmetry breaking of the new matter state enables it to respond sensitively to the polarity of an electric field. Here, we report on the observation of a sequential polar winding/unwinding process of polarization helices under an electric field applied perpendicular to the helical axes, which behaves distinctly from the unwinding of the apolar cholesteric helices. Understanding the helix-unwinding behaviors provides insights for developing switchable devices based on helielectric nematics.
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Affiliation(s)
- Satoshi Aya
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China
- Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou 510640, China.
| | - Hao Xu
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China
- Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou 510640, China.
| | - Huaqian Long
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China
- Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou 510640, China.
| | - Muhan Yiliu
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China
- Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou 510640, China.
| | - Yu Zou
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China
- Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou 510640, China.
| | - Mingjun Huang
- South China Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China
- Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou 510640, China.
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7
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Máthé MT, Perera K, Buka Á, Salamon P, Jákli A. Fluid Ferroelectric Filaments. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2305950. [PMID: 38126584 PMCID: PMC10916631 DOI: 10.1002/advs.202305950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 11/01/2023] [Indexed: 12/23/2023]
Abstract
Freestanding slender fluid filaments of room-temperature ferroelectric nematic liquid crystals are described. They are stabilized either by internal electric fields of bound charges formed due to polarization splay or by external voltage applied between suspending wires. The phenomenon is similar to those observed in dielectric fluids, such as deionized water, except that in ferroelectric nematic materials the voltages required are three orders of magnitudes smaller and the aspect ratio is much higher. The observed ferroelectric fluid threads are not only unique and novel but also offer measurements of basic physical quantities, such as the ferroelectric polarization and viscosity. Ferroelectric nematic fluid threads may have practical applications in nano-fluidic micron-size logic devices, switches, and relays.
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Affiliation(s)
- Marcell T. Máthé
- Institute for Solid State Physics and OpticsWigner Research Centre for PhysicsP.O. Box 49BudapestH‐1525Hungary
- Eötvös Loránd UniversityP.O. Box 32BudapestH‐1518Hungary
| | - Kelum Perera
- Department of PhysicsKent State UniversityKentOH44242USA
| | - Ágnes Buka
- Institute for Solid State Physics and OpticsWigner Research Centre for PhysicsP.O. Box 49BudapestH‐1525Hungary
| | - Péter Salamon
- Institute for Solid State Physics and OpticsWigner Research Centre for PhysicsP.O. Box 49BudapestH‐1525Hungary
| | - Antal Jákli
- Department of PhysicsKent State UniversityKentOH44242USA
- Materials Sciences Graduate Program and Advanced Materials and Liquid Crystal InstituteKent State UniversityKentOH44242USA
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8
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Emelyanenko AV, Rudyak VY, Shvetsov SA, Araoka F, Nishikawa H, Ishikawa K. Transformation of polar nematic phases in the presence of an electric field. Phys Rev E 2024; 109:014701. [PMID: 38366416 DOI: 10.1103/physreve.109.014701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Accepted: 12/07/2023] [Indexed: 02/18/2024]
Abstract
Only a few years have passed since the discovery of polar nematics, and now they are becoming the most actively studied liquid-crystal materials. Despite numerous breakthrough findings made recently, a theoretical systematization is still lacking. In the present paper, we take a step toward systematization. The powerful technique of molecular-statistical physics has been applied to an assembly of polar molecules influenced by electric field. Three polar nematic phases were found to be stable at various conditions: the double-splay ferroelectric nematic N_{F}^{2D} (observed in the lower-temperature range in the absence of or at low electric field), the double-splay antiferroelectric nematic N_{AF} (observed at intermediate temperature in the absence of or at low electric field), and the single-splay ferroelectric nematic N_{F}^{1D} (observed at moderate electric field at any temperature below transition into paraelectric nematic N and in the higher-temperature range (also below N) at low electric field or without it. A paradoxical transition from N_{F}^{1D} to N induced by application of higher electric field has been found and explained. A transformation of the structure of polar nematic phases at the application of electric field has also been investigated by Monte Carlo simulations and experimentally by observation of polarizing optical microscope images. In particular, it has been realized that, at planar anchoring, N_{AF} in the presence of a moderate out-of-plane electric field exhibits twofold splay modulation: antiferroelectric in the plane of the substrate and ferroelectric in the plane normal to the substrate. Several additional subtransitions related to fitting the confined geometry of the cell by the structure of polar phases were detected.
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Affiliation(s)
| | - V Yu Rudyak
- Lomonosov Moscow State University, Moscow 119991, Russia
| | - S A Shvetsov
- Lomonosov Moscow State University, Moscow 119991, Russia
| | - F Araoka
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa Wako, Saitama 351-0198, Japan
| | - H Nishikawa
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa Wako, Saitama 351-0198, Japan
| | - K Ishikawa
- Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
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9
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Park G, Choi YS, Kwon SJ, Yoon DK. Planar Spin Glass with Topologically Protected Mazes in the Liquid Crystal Targeting for Reconfigurable Micro Security Media. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2303077. [PMID: 37148534 DOI: 10.1002/adma.202303077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 12/12/2012] [Indexed: 05/08/2023]
Abstract
The planar spin glass pattern is widely known for its inherent randomness, resulting from the geometrical frustration. As such, developing physical unclonable functions (PUFs)-which operate with device randomness-with planar spin glass patterns is a promising candidate for an advanced security systems in the upcoming digitalized society. Despite their inherent randomness, traditional magnetic spin glass patterns pose considerable obstacles in detection, making it challenging to achieve authentication in security systems. This necessitates the development of facilely observable mimetic patterns with similar randomness to overcome these challenges. Here, a straightforward approach is introduced using a topologically protected maze pattern in the chiral liquid crystals (LCs). This maze exhibits a comparable level of randomness to magnetic spin glass and can be reliably identified through the combination of optical microscopy with machine learning-based object detection techniques. The "information" embedded in the maze can be reconstructed through thermal phase transitions of the LCs in tens of seconds. Furthermore, incorporating various elements can enhance the optical PUF, resulting in a multi-factor security medium. It is expected that this security medium, based on microscopically controlled and macroscopically uncontrolled topologically protected structures, may be utilized as a next-generation security system.
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Affiliation(s)
- Geonhyeong Park
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Yun-Seok Choi
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - S Joon Kwon
- School of Chemical Engineering, Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
- SKKU Institute of Energy Science & Technology (SIEST), Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
- KAIST Institute for Nanocentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Dong Ki Yoon
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
- Department of Semiconductor Convergence Engineering, Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
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10
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Liu JC, Ai Y, Liu Q, Zeng YP, Chen XG, Lv HP, Xiong RG, Liao WQ. Solid-Liquid Crystal Biphasic Ferroelectrics with Tunable Biferroelectricity. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2302436. [PMID: 37202898 DOI: 10.1002/adma.202302436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 04/27/2023] [Indexed: 05/20/2023]
Abstract
Ferroelectricity has been separately found in numerous solid and liquid crystal materials since its first discovery in 1920. However, a single material with biferroelectricity existing in both solid and liquid crystal phases is very rare, and the regulation of biferroelectricity has never been studied. Here, solid-liquid crystal biphasic ferroelectrics, cholestanyl 4-X-benzoate (4X-CB, X = Cl, Br, and I), which exhibits biferroelectricity in both the solid and liquid crystal phases, is presented. It is noted that the ferroelectric liquid crystal phase of 4X-CB is a cholesteric one, distinct from the ordinary chiral smectic ferroelectric liquid crystal phase. Moreover, 4X-CB shows solid-solid and solid-liquid crystal phase transitions, of which the transition temperatures gradually increase from Cl to Br to I substitution. The spontaneous polarization (Ps ) of 4X-CB in both solid and liquid crystal phases can also be regulated by different halogen substitutions, where the 4Br-CB has the optimal Ps because of the larger molecular dipole moment. To the authors' knowledge, 4X-CB is the first ferroelectric with tunable biferroelectricity, which offers a feasible case for the performance optimization of solid-liquid crystal biphasic ferroelectrics.
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Affiliation(s)
- Jun-Chao Liu
- Ordered Matter Science Research Center, Nanchang University, Nanchang, 330031, P. R. China
| | - Yong Ai
- Ordered Matter Science Research Center, Nanchang University, Nanchang, 330031, P. R. China
| | - Qin Liu
- Ordered Matter Science Research Center, Nanchang University, Nanchang, 330031, P. R. China
| | - Yi-Piao Zeng
- Ordered Matter Science Research Center, Nanchang University, Nanchang, 330031, P. R. China
| | - Xiao-Gang Chen
- Ordered Matter Science Research Center, Nanchang University, Nanchang, 330031, P. R. China
| | - Hui-Peng Lv
- Ordered Matter Science Research Center, Nanchang University, Nanchang, 330031, P. R. China
| | - Ren-Gen Xiong
- Ordered Matter Science Research Center, Nanchang University, Nanchang, 330031, P. R. China
| | - Wei-Qiang Liao
- Ordered Matter Science Research Center, Nanchang University, Nanchang, 330031, P. R. China
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11
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Zhou J, Zou Y, Li J, Huang M, Aya S. Spontaneous periodic polarization wave in helielectric fluids. PNAS NEXUS 2023; 2:pgad265. [PMID: 37614674 PMCID: PMC10443924 DOI: 10.1093/pnasnexus/pgad265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 07/31/2023] [Indexed: 08/25/2023]
Abstract
By analogy with spin waves in ferromagnetic systems, the polarization (or dipole) wave is the electric counterpart that remains elusive. Here, we discover that the helielectricity, i.e. a polarization field with helicoidal helices that corresponds to a quasi-layered chiral nematic environment, causes a spontaneous formation of large-scale polarization waves in the form of the sinusoidal function. Both experimental and theoretical analyses reveal that the polarization ordering over a threshold polarization strength violates the inherent periodicity of the polarization helices, thus penalizing the compression energy. It drives a second-order structural transition to a periodically modulated polarization wave state. The roles of chirality and confinement condition are discussed.
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Affiliation(s)
- Junchen Zhou
- Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China
| | - Yu Zou
- Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China
| | - Jinxing Li
- Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China
| | - Mingjun Huang
- Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China
- Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou 510640, China
| | - Satoshi Aya
- Advanced Institute for Soft Matter Science and Technology (AISMST), School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China
- Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology, Guangzhou 510640, China
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12
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Máthé MT, Farkas B, Péter L, Buka Á, Jákli A, Salamon P. Electric field-induced interfacial instability in a ferroelectric nematic liquid crystal. Sci Rep 2023; 13:6981. [PMID: 37117269 PMCID: PMC10147939 DOI: 10.1038/s41598-023-34067-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Accepted: 04/24/2023] [Indexed: 04/30/2023] Open
Abstract
Studies of sessile droplets and fluid bridges of a ferroelectric nematic liquid crystal in externally applied electric fields are presented. It is found that above a threshold, the interface of the fluid with air undergoes a fingering instability or ramification, resembling to Rayleigh-type instability observed in charged droplets in electric fields or circular drop-type instabilities observed in ferromagnetic liquids in magnetic field. The frequency dependence of the threshold voltage was determined in various geometries. The nematic director and ferroelectric polarization direction was found to point along the tip of the fingers that appear to repel each other, indicating that the ferroelectric polarization is essentially parallel to the director. The results are interpreted in connection to the Rayleigh and circular drop-type instabilities.
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Affiliation(s)
- Marcell Tibor Máthé
- Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, P.O. Box 49, Budapest, 1525, Hungary
- Eötvös Loránd University, P.O. Box 32, 1518, Budapest, Hungary
| | - Bendegúz Farkas
- Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, P.O. Box 49, Budapest, 1525, Hungary
- Eötvös Loránd University, P.O. Box 32, 1518, Budapest, Hungary
| | - László Péter
- Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, P.O. Box 49, Budapest, 1525, Hungary
| | - Ágnes Buka
- Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, P.O. Box 49, Budapest, 1525, Hungary
| | - Antal Jákli
- Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, P.O. Box 49, Budapest, 1525, Hungary.
- Materials Sciences Graduate Program and Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH, 44242, USA.
- Department of Physics, Kent State University, Kent, OH, 44242, USA.
| | - Péter Salamon
- Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, P.O. Box 49, Budapest, 1525, Hungary.
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Yu JS, Lee JH, Lee JY, Kim JH. Alignment properties of a ferroelectric nematic liquid crystal on the rubbed substrates. SOFT MATTER 2023; 19:2446-2453. [PMID: 36939059 DOI: 10.1039/d3sm00123g] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
The orientation characteristics of FNLC-919, a new material with a ferroelectric nematic phase at room temperature, were investigated. Its alignment characteristics varied greatly depending on the relative rubbing direction on both substrates of a liquid crystal cell. In a cell where the two substrates were rubbed in the same direction, they were arranged homogeneously along the rubbing direction without domains or defects in the ferroelectric nematic phase. In a cell where the two substrates were rubbed in the anti-parallel direction, the two domains were twisted in the opposite direction. We quantitatively obtained the twisted direction and angle by matching the experimental data and calculation results using Jones matrix calculations. From the electro-optical experiment, it was confirmed that the polarization direction was opposite to the rubbing direction. In addition, the wavelength and temperature dependence of birefringence was measured for FNLC-919. In a cell where the rubbing direction between two substrates was 90°, two domains of opposite directions were observed in the nematic phase. When it becomes a ferroelectric nematic phase on cooling, the twist is determined to be only in one direction. The twist direction and angle were quantitatively obtained in the nematic and ferroelectric nematic phases. It was twisted more in the ferroelectric nematic phase than in the nematic phase.
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Affiliation(s)
- Jeong-Seon Yu
- Institute of Quantum Systems, Chungnam National University, Daejeon, 34134, Korea.
| | - Jae Hoon Lee
- Department of Physics, Chungnam National University, Daejeon, 34134, Korea
| | - Jun-Yong Lee
- Department of Physics, Chungnam National University, Daejeon, 34134, Korea
| | - Jong-Hyun Kim
- Institute of Quantum Systems, Chungnam National University, Daejeon, 34134, Korea.
- Department of Physics, Chungnam National University, Daejeon, 34134, Korea
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