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Nordendorf G, Jünnemann-Held G, Lorenz A, Kitzerow HS. Effects of Composition and Polymerization Conditions on the Electro-Optic Performance of Liquid Crystal-Polymer Composites Doped with Ferroelectric Nanoparticles. NANOMATERIALS (BASEL, SWITZERLAND) 2024; 14:961. [PMID: 38869586 PMCID: PMC11173507 DOI: 10.3390/nano14110961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2024] [Revised: 05/21/2024] [Accepted: 05/27/2024] [Indexed: 06/14/2024]
Abstract
The presence of a polymer network and/or the addition of ferroelectric nanoparticles to a nematic liquid crystal are found to lower transition temperatures and birefringence, which indicates reduced orientational order. In addition, the electro-optic switching voltage is considerably increased when a polymer network is formed by in situ polymerization in the nematic state. However, the resulting polymer network liquid crystal switches at similar voltages as the neat liquid crystal when polymerization is performed at an elevated temperature in the isotropic state. When nanoparticle dispersions are polymerized at an applied DC voltage, the transition temperatures and switching voltages are reduced, yet they are larger than those observed for polymer network liquid crystals without nanoparticles polymerized in the isotropic phase.
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Affiliation(s)
- Gaby Nordendorf
- Department of Chemistry, Faculty of Science, Paderborn University, Warburger Str. 100, 33098 Paderborn, Germany; (G.N.); (G.J.-H.); (A.L.)
- Center for Optoelectronics and Photonics Paderborn (CeOPP), Paderborn University, Warburger Str. 100, 33098 Paderborn, Germany
| | - Gisela Jünnemann-Held
- Department of Chemistry, Faculty of Science, Paderborn University, Warburger Str. 100, 33098 Paderborn, Germany; (G.N.); (G.J.-H.); (A.L.)
| | - Alexander Lorenz
- Department of Chemistry, Faculty of Science, Paderborn University, Warburger Str. 100, 33098 Paderborn, Germany; (G.N.); (G.J.-H.); (A.L.)
- COVDEAG-CCO-SF-GV-AD, Covestro Deutschland AG, 51365 Leverkusen, Germany
| | - Heinz-Siegfried Kitzerow
- Department of Chemistry, Faculty of Science, Paderborn University, Warburger Str. 100, 33098 Paderborn, Germany; (G.N.); (G.J.-H.); (A.L.)
- Center for Optoelectronics and Photonics Paderborn (CeOPP), Paderborn University, Warburger Str. 100, 33098 Paderborn, Germany
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2
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Oropesa WGC, Nascimento ES, Vieira AP. Mean-field model for a mixture of biaxial nematogens and dipolar nanoparticles. Phys Rev E 2024; 109:054701. [PMID: 38907419 DOI: 10.1103/physreve.109.054701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 03/27/2024] [Indexed: 06/24/2024]
Abstract
We analyze a mean-field model for mixtures involving biaxial nematogens and dipolar nanoparticles, taking into account not only orientational and isotropic pair interactions between nematogens but also orientational nematogen-nanoparticle interactions. We determine bulk equilibrium phase diagrams for a wide range of interaction strengths, identifying in each case the effect of the nanoparticles on the stability of nematic phases and on the appearance of multicritical points. Special attention is given to the limit of a low concentration of nanoparticles, in which their effect on the temperatures of both the first-order uniaxial-isotropic and the continuous biaxial-uniaxial transitions is investigated in detail.
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Affiliation(s)
- William G C Oropesa
- Universidade de São Paulo, Instituto de Fisica, Rua do Matao, 1371, 05508-090 São Paulo, SP, Brazil
- ICTP South American Institute for Fundamental Research, Instituto de Física Teórica, UNESP-Universidade Estadual Paulista, Rua Doutor Bento Teobaldo Ferraz 271, 01140-070 São Paulo, SP, Brazil
| | - Eduardo S Nascimento
- Departamento de Física, PUC-Rio, Rua Marquês de São Vicente 225, 22453-900 Rio de Janeiro, Rio de Janeiro, Brazil
| | - André P Vieira
- Universidade de São Paulo, Instituto de Fisica, Rua do Matao, 1371, 05508-090 São Paulo, SP, Brazil
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3
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Atata SB, Lelidis I. Exploring Quantum Dots Size Impact at Phase Diagram and Electrooptical Properties in 8CB Liquid Crystal Soft-Nanocomposites. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:2980. [PMID: 37999334 PMCID: PMC10674785 DOI: 10.3390/nano13222980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 11/08/2023] [Accepted: 11/17/2023] [Indexed: 11/25/2023]
Abstract
We explore the influence of functionalized core-shell CdSe/ZnS quantum dots on the properties of the host liquid crystal compound 4-cyano-4'-octylbiphenyl (8CB) through electrooptical measurements. Two different diameters of quantum dots are used to investigate the size effects. We assess both the dispersion quality of the nanoparticles within the mixtures and the phase stability of the resulting anisotropic soft nanocomposites using polarizing optical microscopy. The temperature-mass fraction phase diagrams of the nanocomposites reveal deviations from the linear behavior in the phase stability lines. We measure the birefringence, the threshold voltage of the Fréedericksz transition, and the electrooptic switching times of the nanocomposite systems in planar cell geometry as functions of temperature, mass fraction, and diameter of the quantum dots. Beyond a critical mass fraction of the dopant nanoparticles, the nematic order is strongly reduced. Furthermore, we investigate the impact of the nanoparticle size and mass fraction on the viscoelastic coefficient. The anchoring energy at the interfaces of the liquid crystal with the cell and the quantum dots is estimated.
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Affiliation(s)
| | - Ioannis Lelidis
- Faculty of Physics, National and Kapodistrian University of Athens, Panepistimiopolis, Zografos, 15784 Athens, Greece
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4
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Indium tin oxide nanoparticles induced tunable dual alignment in nematic liquid crystal. J Mol Liq 2023. [DOI: 10.1016/j.molliq.2023.121264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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5
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Kovalchuk O, Kovalchuk T, Tomašovičová N, Timko M, Zakutanska K, Miakota D, Kopčanský P, Shevchuk O, Garbovskiy Y. Dielectric and electrical properties of nematic liquid crystals 6CB doped with iron oxide nanoparticles. The combined effect of nanodopant concentration and cell thickness. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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6
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Anu, Varshney D, Yadav K, Prakash J, Meena H, Singh G. Tunable dielectric and memory features of ferroelectric layered perovskite Bi4Ti3O12 nanoparticles doped nematic liquid crystal composite. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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7
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Parveen A, Prakash J, Singh G. Impact of strontium titanate nanoparticles on the dielectric, electro-optical and electrical response of a nematic liquid crystal. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.118907] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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8
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Varshney D, Anu, Prakash J, Pratap Singh V, Yadav K, Singh G. Probing the impact of bismuth-titanate based nanocomposite on the dielectric and electro-optical features of a nematic liquid crystal material. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2021.118389] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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9
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Nanoparticle-Induced Property Changes in Nematic Liquid Crystals. NANOMATERIALS 2022; 12:nano12030341. [PMID: 35159688 PMCID: PMC8839905 DOI: 10.3390/nano12030341] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/18/2022] [Accepted: 01/18/2022] [Indexed: 11/30/2022]
Abstract
Doping liquid crystals with nanoparticles is a widely accepted method to enhance liquid crystal’s intrinsic properties. In this study, a quick and reliable method to characterise such colloidal suspensions using an optical multi-parameter analyser, a cross-polarised intensity measurement-based device, is presented. Suspensions characterised in this work are either plasmonic (azo-thiol gold AzoGNPs) or ferroelectric Sn2P2S6 (SPS) nanoparticles in nematic liquid crystals. The elastic constants and rotational viscosity showed nonlinear dependence on the concentration of AzoGNPs, initially increasing at lower concentrations and then decreasing at higher concentrations, indicating some degree of particle aggregation. For the SPS suspension, the elastic constant decreased with doping, while the rotational viscosity increased, in agreement with previous findings. Through viscosity measurements, the stability of SPS suspension over ten years is also highlighted.
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Makovec D, Križaj N, Gyergyek S. Hydrothermal formation of bismuth-titanate nanoplatelets and nanowires: the role of metastable polymorphs. CrystEngComm 2022. [DOI: 10.1039/d2ce00491g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Understanding the processes involved in the formation of nanoparticles is a prerequisite for the control of their morphology. In this investigation we reveal the processes leading to the formation of...
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11
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Kumar A, Kwatra P, Meena H, Prakash J, Wang L, Singh G. Recent advances on semiconducting nanomaterials-ferroelectric liquid crystals nanocomposites. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 34:013004. [PMID: 34584020 DOI: 10.1088/1361-648x/ac2ace] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Ferroelectric liquid crystals (FLCs) possess excellent electro-optical properties compared to nematic liquid crystals including lower threshold voltage, faster switching response, good optical contrast and bi-stable switching, memory effect, etc. Due to such characteristic features, FLCs are more promising for next generation high performance photonic applications. Moreover, the synergy of FLCs with nanoscience has clearly shown the enormous possibilities to improve upon their electro-optical properties. Over the past two decades, several investigations of nanomaterial (metal, metal oxide, ferroelectric, insulating, graphene, semiconducting etc.) dispersed FLC nanocomposites have been carried out. Semiconducting nanomaterials (SNMs), exhibiting quantum confinement effect, have been one of the most explored nanomaterials as dopants in FLCs leading to better molecular alignment, enhanced dielectric behavior, pronounced memory effect, power efficient, faster switching response and enhanced photoluminescence. Here, we present a focused review on SNMs-FLCs nanocomposites and propose future work to advance liquid crystal nanoscience.
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Affiliation(s)
- Ajay Kumar
- Physics, Dr Bhim Rao Ambedkar University, Aligarh, Agra, Uttar Pradesh, 282004, INDIA
| | - Priyam Kwatra
- Department of Applied Physics, Amity Institute of Applied Sciences, Amity University, E1 Block, AIAS, Amity University, Noida (U.P.), Noida, Noida, Uttar Pradesh, 201303, INDIA
| | - Harikesh Meena
- Department of Applied Physics, Amity Institute of Applied Sciences, Amity University, E1 Block, AIAS, Amity University, Noida (U.P.), Noida, Noida, Uttar Pradesh, 201303, INDIA
| | - Jai Prakash
- Physics, Aligarh Muslim University, Department of Physics, AMU, Aligarh, Aligarh, 202002, INDIA
| | - Ling Wang
- School of Materials Science and Engineering, Tianjin University, Tianjin 300350, PR China, Tianjin, Tianjin, 300072, CHINA
| | - Gautam Singh
- Department of Applied Physics, Amity University, E1 Block, Room No. E1-312D, AIAS, Amity University, Noida (U.P.), Noida, Noida, Uttar Pradesh, 201304, INDIA
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12
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Pristine and ferroelectric liquid crystal dispersed four ring bent core nematic: Impact of dispersion on electro-optic and dielectric properties. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.115955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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13
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Effect of γ-irradiation on various important physical properties of a room temperature ferroelectric liquid crystal mixture and its silver nanocomposite. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.115628] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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14
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Garbovskiy Y. Conventional and unconventional ionic phenomena in tunable soft materials made of liquid crystals and nanoparticles. NANO EXPRESS 2021. [DOI: 10.1088/2632-959x/abe652] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Abstract
A great variety of tunable multifunctional materials can be produced by combining nanoparticles and liquid crystals. Typically, the tunability of such soft nanocomposites is achieved via external electric fields resulting in the field-induced reorientation of liquid crystals. This reorientation can be altered by ions normally present in liquid crystals in small quantities. In addition, nanomaterials dispersed in liquid crystals can also affect the behavior of ions. Therefore, an understanding of ionic phenomena in liquid crystals doped with nanoparticles is essential for future advances in liquid crystal-aided nanoscience and nanotechnology. This paper provides an overview of the ionic effects observed in liquid crystals doped with nanomaterials. An introduction to liquid crystals is followed by a brief overview of nanomaterials in liquid crystals. After giving a basic description of ions in liquid crystals and experimental methods to measure them, a wide range of ionic phenomena in liquid crystals doped with different types of nanomaterials is discussed. After that, both existing and emerging applications of tunable soft materials made of liquid crystals and nanodopants are presented with an emphasis on the role of ionic effects in such systems. Finally, the discussion of unsolved problems and future research directions completes the review.
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15
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Ferroelectric Particles in Nematic Liquid Crystals with Soft Anchoring. Molecules 2021; 26:molecules26041166. [PMID: 33671776 PMCID: PMC7926494 DOI: 10.3390/molecules26041166] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 02/16/2021] [Accepted: 02/18/2021] [Indexed: 11/30/2022] Open
Abstract
A theoretical evaluation of the electric Freedericksz transition threshold and saturation field is proposed for a liquid crystals composite with ferroelectric particles. Existing models consider a strong anchoring of nematic molecules on the glass support of the cell, but in this paper a soft molecular anchoring of molecules on the glass support and also on the ferroelectric nanoparticle’s surface is assumed. Thus, a finite saturation field was obtained in agreement with real systems. Calculations are made for planar configuration of positive dielectric anisotropy liquid crystals. The results are compared with data obtained on similar systems from different publications and the differences are discussed.
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16
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The influence of nanoparticles on phase formation and stability of liquid crystals and liquid crystalline polymers. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2020.114849] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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17
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Enhanced electrochemical and electro-optical properties of nematic liquid crystal doped with Ni:ZnCdS/ZnS core/shell quantum dots. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.114373] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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18
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Rzoska SJ, Starzonek S, Łoś J, Drozd-Rzoska A, Kralj S. Dynamics and Pretransitional Effects in C 60 Fullerene Nanoparticles and Liquid Crystalline Dodecylcyanobiphenyl (12CB) Hybrid System. NANOMATERIALS (BASEL, SWITZERLAND) 2020; 10:E2343. [PMID: 33255904 PMCID: PMC7761475 DOI: 10.3390/nano10122343] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 11/15/2020] [Accepted: 11/16/2020] [Indexed: 11/16/2022]
Abstract
The report shows the strong impact of fullerene C60 nanoparticles on phase transitions and complex dynamics of rod-like liquid crystal dodecylcyanobiphenyl (12CB), within the limit of small concentrations. Studies were carried out using broadband dielectric spectroscopy (BDS) via the analysis of temperature dependences of the dielectric constant, the maximum of the primary loss curve, and relaxation times. They revealed a strong impact of nanoparticles, leading to a ~20% change of dielectric constant even at x = 0.05% of C60 fullerene. The application of the derivative-based and distortion-sensitive analysis showed that pretransitional effects dominate in the isotropic liquid phase up to 65 K above the clearing temperature and in the whole Smectic A mesophase. The impact of nanoparticles on the pretransitional anomaly appearance is notable for the smectic-solid phase transition. The fragility-based analysis of relaxation times revealed the universal pattern of its temperature changes, associated with scaling via the "mixed" ("activated" and "critical") relation. Phase behavior and dynamics of tested systems are discussed within the extended Landau-de Gennes-Ginzburg mesoscopic approach.
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Affiliation(s)
- Sylwester J. Rzoska
- Institute of High Pressure Physics Polish Academy of Sciences, Sokołowska 29/37, 01-142 Warsaw, Poland; (S.S.); (J.Ł.); (A.D.-R.)
| | - Szymon Starzonek
- Institute of High Pressure Physics Polish Academy of Sciences, Sokołowska 29/37, 01-142 Warsaw, Poland; (S.S.); (J.Ł.); (A.D.-R.)
| | - Joanna Łoś
- Institute of High Pressure Physics Polish Academy of Sciences, Sokołowska 29/37, 01-142 Warsaw, Poland; (S.S.); (J.Ł.); (A.D.-R.)
| | - Aleksandra Drozd-Rzoska
- Institute of High Pressure Physics Polish Academy of Sciences, Sokołowska 29/37, 01-142 Warsaw, Poland; (S.S.); (J.Ł.); (A.D.-R.)
| | - Samo Kralj
- Laboratory of Physics of Complex Systems, Faculty of Natural Sciences and Mathematics, University of Maribor, Koroška 160, 2000 Maribor, Slovenia;
- Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
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19
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Varshney D, Parveen A, Prakash J. Effect of cobalt oxide nanoparticles on dielectric properties of a nematic liquid crystal material. J DISPER SCI TECHNOL 2020. [DOI: 10.1080/01932691.2020.1813591] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Depanshu Varshney
- Department of Physics, Aligarh Muslim University, Aligarh, Uttar Pradesh, India
| | - Ariba Parveen
- Department of Physics, Aligarh Muslim University, Aligarh, Uttar Pradesh, India
| | - Jai Prakash
- Department of Physics, Aligarh Muslim University, Aligarh, Uttar Pradesh, India
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20
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Garbovskiy Y, Emelyanenko AV, Glushchenko A. Inverse "guest-host" effect: ferroelectric nanoparticles mediated switching of nematic liquid crystals. NANOSCALE 2020; 12:16438-16442. [PMID: 32756694 DOI: 10.1039/d0nr05301e] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Liquid crystals are widely used as a host matrix to embed different materials: dyes, fullerenes, carbon nanotubes, various nanoparticles (metallic, semiconductor, ferromagnetic, ferroelectric). The usual approach is related to the so called "guest-host" effect: external electric (or magnetic) fields drive liquid crystals (host), and liquid crystals reorient embedded particles (guest). In this paper we report an experimental observation of the effect that is completely opposite to the classical "guest-host" phenomenon: ferroelectric nanoparticles being switched by an external field mediate the switching of liquid crystals. Our experiments show that ferroelectric nanoparticles reorient and hold liquid crystal molecules in a direction of the ferroelectric nanoparticles orientation even when an external electric field attempts to orient a liquid crystal in an orthogonal direction.
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Affiliation(s)
- Y Garbovskiy
- Department of Physics and Engineering Physics, Central Connecticut State University, New Britain, CT 06050, USA.
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21
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Microwave Liquid Crystal Enabling Technology for Electronically Steerable Antennas in SATCOM and 5G Millimeter-Wave Systems. CRYSTALS 2020. [DOI: 10.3390/cryst10060514] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Future satellite platforms and 5G millimeter wave systems require Electronically Steerable Antennas (ESAs), which can be enabled by Microwave Liquid Crystal (MLC) technology. This paper reviews some fundamentals and the progress of microwave LCs concerning its performance metric, and it also reviews the MLC technology to deploy phase shifters in different topologies, starting from well-known toward innovative concepts with the newest results. Two of these phase shifter topologies are dedicated for implementation in array antennas: (1) wideband, high-performance metallic waveguide phase shifters to plug into a waveguide horn array for a relay satellite in geostationary orbit to track low Earth orbit satellites with maximum phase change rates of 5.1°/s to 45.4°/s, depending on the applied voltages, and (2) low-profile planar delay-line phase shifter stacks with very thin integrated MLC varactors for fast tuning, which are assembled into a multi-stack, flat-panel, beam-steering phased array, being able to scan the beam from −60° to +60° in about 10 ms. The loaded-line phase shifters have an insertion loss of about 3 dB at 30 GHz for a 400° differential phase shift and a figure-of-merit (FoM) > 120°/dB over a bandwidth of about 2.5 GHz. The critical switch-off response time to change the orientation of the microwave LCs from parallel to perpendicular with respect to the RF field (worst case), which corresponds to the time for 90 to 10% decay in the differential phase shift, is in the range of 30 ms for a LC layer height of about 4 µm. These MLC phase shifter stacks are fabricated in a standard Liquid Crystal Display (LCD) process for manufacturing low-cost large-scale ESAs, featuring single- and multiple-beam steering with very low power consumption, high linearity, and high power-handling capability. With a modular concept and hybrid analog/digital architecture, these smart antennas are flexible in size to meet the specific requirements for operating in satellite ground and user terminals, but also in 5G mm-wave systems.
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22
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Parveen A, Varshney D, Prakash J. Nematic liquid crystal/dimethylsulphoxide mixture based tuning condenser. IOP SCINOTES 2020. [DOI: 10.1088/2633-1357/ab8bc2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abstract
Here, we demonstrate experimentally the existence of temporally variable dielectric behavior of a nematic liquid crystal (NLC), the most widely used liquid crystal (LC) phase among all LCs materials, by mixing dimethylsulphoxide (DMSO) into former. The intermolecular interactions and nanosegregation of the molecular LC structures have influenced their self-assembly by mixing DMSO into it. We mainly examined the dielectric parameters such as dielectric permittivity, dielectric loss factor, and absorption/energy dissipation and observed that the NLC/DMSO mixture shows a nearly dielectric-conductor (D-C) transition as time passes. The presence of DMSO in this analysis was confirmed by Fourier transform infrared spectroscopy while time-dependent dielectric studies were carried out using dielectric spectroscopic techniques. The promising idea of showing D-C transition is truly proven that may open the possibilities for real-time variable and supercapacitors.
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23
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On the Analogy between Electrolytes and Ion-Generating Nanomaterials in Liquid Crystals. NANOMATERIALS 2020; 10:nano10030403. [PMID: 32106491 PMCID: PMC7152844 DOI: 10.3390/nano10030403] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 02/18/2020] [Accepted: 02/19/2020] [Indexed: 12/20/2022]
Abstract
Nanomaterials in liquid crystals are a hot topic of contemporary liquid crystal research. An understanding of the possible effects of nanodopants on the properties of liquid crystals is critical for the development of novel mesogenic materials with improved functionalities. This paper focuses on the electrical behavior of contaminated nanoparticles in liquid crystals. More specifically, an analogy between electrolytes and ion-generating nanomaterials in liquid crystals is established. The physical consequences of this analogy are analyzed. Under comparable conditions, the number of ions generated by nanomaterials in liquid crystals can be substantially greater than the number of ions generated by electrolytes of similar concentration.
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Uhl AM, Andrew JS. Sol-Gel-Based Electrospray Synthesis of Barium Titanate Nanoparticles. IEEE Trans Nanobioscience 2020; 19:162-166. [PMID: 31905140 DOI: 10.1109/tnb.2019.2963165] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Barium titanate nanoparticles are desirable for a wide range of applications, spanning electronics to biomedicine. Here, we present an electrospray-based method for the synthesis of barium titanate nanomaterials, where their morphology can be altered, forming either particles or rods. As-electrosprayed particles are amorphous and spherical, but upon calcination in the presence of sodium chloride their morphology can vary from particles to rods as the calcination time is increased. The processing-structure-property relationships in these materials are discussed.
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Prakash J, Khan S, Chauhan S, Biradar A. Metal oxide-nanoparticles and liquid crystal composites: A review of recent progress. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2019.112052] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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26
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Samoilov A, Minenko S, Sushynskyi O, Lisetski L, Lebovka N. Optical and calorimetric studies of quercetin-doped liquid crystals: Effects of molecular aggregation. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2019.111689] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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27
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Guo Y, Li W, Li X, Zhang H, Ma H, Sun Y. Influences of nickel plated multi-walled carbon-nanotube on the electro-optical properties of nematic liquid crystal. NANOTECHNOLOGY 2019; 30:475201. [PMID: 31434061 DOI: 10.1088/1361-6528/ab3d4c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Some enhanced performances can be obtained by doping multi-walled carbon-nanotube (MWCNT) into self-organized nematic liquid crystal (NLC). However, the dispersion of MWCNT in NLC is very few, thus the enhancement is restricted. In this work, a nickel plated MWCNT (MWCNT@Ni) is synthesized to obtain a relatively high dispersion. The morphology, element and chemical bond differences between MWCNT and MWCNT@Ni are characterized. For MWCNT@Ni, there is a layer of coaxial nickel coated on the surface of MWCNT, which weakens the interaction energy between the adjacent MWCNTs and further results in a relatively high dispersion. Moreover, MWCNT@Ni has a more orderly arrangement in NLC compared with MWCNT. The results suggest that the dielectric anisotropy of MWCNT@Ni/NLC with mass fraction of 0.01 wt% is increased by ∼3.6%, and the saturation voltage is reduced by ∼7.3%. Besides, the rise time is decreased by ∼9.5% at 5 V and 1 kHz. These performances have been improved compared with MWCNT/NLC under the same mass fraction. The effect of mass fraction of MWCNT@Ni on rise time is further investigated. As a result, the rise time is decreased by ∼16.7% as MWCNT@Ni with mass fraction of 0.10 wt% is added into NLC. In general, the method to increase dispersion of dopant in NLC is proposed, which can serve as a reference to improve the performances of NLC composites.
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Affiliation(s)
- Yuqiang Guo
- School of Electronic and Information Engineering, Hebei University of Technology, Tianjin 300401, People's Republic of China. Department of Applied Physics, Hebei University of Technology, Tianjin 300401, People's Republic of China
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Impact of Dispersion of Nanoscale Particles on the Properties of Nematic Liquid Crystals. CRYSTALS 2019. [DOI: 10.3390/cryst9090475] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
This work reviews the recent progress made in last decade in understanding the role of dispersion ofnanoparticles and quantum dots into host nematic liquid crystals. There are two important ingredients of this work: Even a minute concentration of these non-mesogenic materials in host matrix can have reflective impact on the dielectric, electro-optical, and spectroscopic properties of host nematics and the nematic-nanoparticles composite systems become suitable for the use in nematic based display and other devices.
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Geier IS, Wandrei SM, Skutnik RA, Schoen M. Molecular theory of a ferromagnetic nematic liquid crystal. Phys Rev E 2019; 100:022702. [PMID: 31574629 DOI: 10.1103/physreve.100.022702] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Indexed: 06/10/2023]
Abstract
We employ a version of classical density functional theory to study the phase behavior of a simple model liquid crystal in an external field. The uniaxially symmetric molecules have a spherically symmetric core with superimposed orientation-dependent attractions. The interaction between the cores consists of a hard-sphere repulsion plus an isotropic square-well attraction. The anisotropic part of the interaction potential allows for the formation of a uniaxially symmetric nematic phase. The orientation of the molecules couples to an external polar field. The external field is capable of rotating the nematic director n[over ̂] in the x-z plane. The field is also capable of changing the topology of the phase diagram in that it suppresses the phase coexistence between an isotropic liquid and a nematic phase observed in the absence of the field. We study the transition from an unpolar to a polar nematic phase in terms of the orientation-distribution function (odf), nematic and polar order parameters, and components of n[over ̂]. If represented suitably the odf allows us to study orientational changes during the switching process between nonpolar and polar nematic phases. We also give a simple argument that explains why nematic order is lost whereas polar order persists up to the gas-liquid critical point along the coexistence curve. We also discuss the relevance of our theory for future experimental studies.
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Affiliation(s)
- Immanuel S Geier
- Stranski-Laboratorium für Physikalische und Theoretische Chemie, Fakultät für Mathematik und Naturwissenschaften, Technische Universität Berlin, Straße des 17. Juni 115, 10623 Berlin, Germany
| | - Stefanie M Wandrei
- Stranski-Laboratorium für Physikalische und Theoretische Chemie, Fakultät für Mathematik und Naturwissenschaften, Technische Universität Berlin, Straße des 17. Juni 115, 10623 Berlin, Germany
| | - Robert A Skutnik
- Stranski-Laboratorium für Physikalische und Theoretische Chemie, Fakultät für Mathematik und Naturwissenschaften, Technische Universität Berlin, Straße des 17. Juni 115, 10623 Berlin, Germany
| | - Martin Schoen
- Stranski-Laboratorium für Physikalische und Theoretische Chemie, Fakultät für Mathematik und Naturwissenschaften, Technische Universität Berlin, Straße des 17. Juni 115, 10623 Berlin, Germany
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
- Department of Chemical and Biomolecular Engineering, Engineering Building I, Box 7905, North Carolina State University, 911 Partners Way, Raleigh, North Carolina 27695, USA
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Drozd-Rzoska A, Starzonek S, Rzoska SJ, Kralj S. Nanoparticle-controlled glassy dynamics in nematogen-based nanocolloids. Phys Rev E 2019; 99:052703. [PMID: 31212529 DOI: 10.1103/physreve.99.052703] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Indexed: 11/07/2022]
Abstract
Results of broad-band dielectric spectroscopy studies in liquid crystal (pentylcyanobiphenyl, 5CB)-based nanocolloids are presented. They reveal the strong impact of BaTiO_{3} nanoparticles on dynamics and uniaxial ordering. Studies were carried out in an extreme range of temperatures (∼150 K), including the supercooled nematic phase. For the latter, the unique "pretransitional" effect for dielectric constant on approaching solid state is reported. The distortion-sensitive analysis revealed super-Arrhenius dynamics but associated with critical-like behavior. In the isotropic phase, translational-orientational decoupling, unusual for the high temperature dynamic domain, was detected. It can be directly link to heterogeneities-prenematic fluctuations. The model linking the classical Landau-de Gennes approach with Imry-Ma arguments has been developed to discuss experimental results.
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Affiliation(s)
- Aleksandra Drozd-Rzoska
- Institute of High Pressure Physics of the Polish Academy of Sciences, ul. Sokołowska 29/37, 01-142 Warsaw, Poland
| | | | | | - Samo Kralj
- Faculty of Natural Sciences and Mathematics, University of Maribor, Koroska 160, 2000 Maribor, Slovenia and Condensed Matter Physics Department, Jozef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
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31
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Perspectives in Liquid-Crystal-Aided Nanotechnology and Nanoscience. APPLIED SCIENCES-BASEL 2019. [DOI: 10.3390/app9122512] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The research field of liquid crystals and their applications is recently changing from being largely focused on display applications and optical shutter elements in various fields, to quite novel and diverse applications in the area of nanotechnology and nanoscience. Functional nanoparticles have recently been used to a significant extent to modify the physical properties of liquid crystals by the addition of ferroelectric and magnetic particles of different shapes, such as arbitrary and spherical, rods, wires and discs. Also, particles influencing optical properties are increasingly popular, such as quantum dots, plasmonic, semiconductors and metamaterials. The self-organization of liquid crystals is exploited to order templates and orient nanoparticles. Similarly, nanoparticles such as rods, nanotubes and graphene oxide are shown to form lyotropic liquid crystal phases in the presence of isotropic host solvents. These effects lead to a wealth of novel applications, many of which will be reviewed in this publication.
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Jessy P, Bambole V, Deshmukh R, Patel N. Reduced power consumption in nickel zinc ferrite nanoparticles doped blue phase chiral nematic liquid crystal devices. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2019.02.098] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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33
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Pappu LM, Martin-Palma R, Martín-Adrados B, Abdulhalim I. Voltage controlled scattering from porous silicon Mie-particles in liquid crystals. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2019.02.085] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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34
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Elkhalgi HH, Khandka S, Yadav N, Dhar R, Dabrowski R. Effects of manganese (II) titanium oxide nano particles on the physical properties of a room temperature nematic liquid crystal 4-(trans-4′-n-hexylcyclohexyl) isothiocyanatobenzene. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2018.07.044] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Kumar P, Debnath S, Rao NVS, Sinha A. Nanodoping: a route for enhancing electro-optic performance of bent core nematic system. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:095101. [PMID: 29336349 DOI: 10.1088/1361-648x/aaa801] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report the effect of dispersion of barium titanate (BaTiO3) nanoparticles (BNPs) in a four ring bent core nematic (BCN) liquid crystal. Polarizing optical microscopy reveals the presence of a single nematic phase in pure and doped states. Polar switching has been observed in the bent core system and the value of spontaneous polarization (P s) increases with increase in doping concentration of BNPs in BCN. Dielectric study shows a lower frequency mode, which can be ascribed to the formation of cybotactic clusters. These clusters are also responsible for the observed polar switching in pure, as well as, in doped BCNs. Another higher frequency mode, observed only in pure BCN, indicates the rotation of molecules about their long molecular axis. The conductivity of doped samples is also found to decrease as compared to the pure BCN. This reduction helps in the minimization of negative effects caused by free ions in liquid crystal based devices. This study demonstrates that the interaction between BNPs and BCN molecules improves the P s, dielectric behaviour, viscosity and reduces the conductivity of pure BCN. Hence, nanodoping in a BCN is an effective method for the enhancement of electro-optic performances and will lead to the development of faster electro-optic devices.
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Affiliation(s)
- Pradeep Kumar
- Department of Physics, Indian Institute of Technology Delhi, 110016, India
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Modifying Thermal Switchability of Liquid Crystalline Nanoparticles by Alkyl Ligands Variation. NANOMATERIALS 2018. [PMID: 29518916 PMCID: PMC5869638 DOI: 10.3390/nano8030147] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
By coating plasmonic nanoparticles (NPs) with thermally responsive liquid crystals (LCs) it is possible to prepare reversibly reconfigurable plasmonic nanomaterials with prospective applications in optoelectronic devices. However, simple and versatile methods to precisely tailor properties of liquid-crystalline nanoparticles (LC NPs) are still required. Here, we report a new method for tuning structural properties of assemblies of nanoparticles grafted with a mixture of promesogenic and alkyl thiols, by varying design of the latter. As a model system, we used Ag and Au nanoparticles that were coated with three-ring promesogenic molecules and dodecanethiol ligand. These LC NPs self-assemble into switchable lamellar (Ag NPs) or tetragonal (Au NPs) aggregates, as determined with small angle X-ray diffraction and transmission electron microscopy. Reconfigurable assemblies of Au NPs with different unit cell symmetry (orthorombic) are formed if hexadecanethiol and 1H,1H,2H,2H-perfluorodecanethiol were used in the place of dodecanethiol; in the case of Ag NPs the use of 11-hydroxyundecanethiol promotes formation of a lamellar structure as in the reference system, although with substantially broader range of thermal stability (140 vs. 90 °C). Our results underline the importance of alkyl ligand functionalities in determining structural properties of liquid-crystalline nanoparticles, and, more generally, broaden the scope of synthetic tools available for tailoring properties of reversibly reconfigurable plasmonic nanomaterials.
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