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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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Kurilov AD, Chausov DN, Osipova VV, Sagdeev DO, Chekulaev IS, Kucherov RN, Belyaev VV, Galyametdinov YG. Concentration-dependent dielectric and electro-optical properties of composites based on nematic liquid crystals and CdS:Mn quantum dots. SOFT MATTER 2023; 19:2110-2119. [PMID: 36857700 DOI: 10.1039/d2sm01352e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Composites in a wide concentration range of 0-0.6 wt% based on a nematic liquid crystal mixture and CdS quantum dots doped with manganese ions (Mn 6%) are presented. The effect of the CdS:Mn quantum dots on the phase diagram and electronic structure of composites was studied using differential scanning calorimetry and fluorescence analysis. Nonmonotonic concentration-dependent changes in the clearing point, which correlate with the fluorescence quenching behavior of the main CdS:Mn peak, were found. Dielectric spectroscopy and electro-optic studies revealed a corresponding increase in the dielectric permittivity anisotropy and birefringence in the 0.2-0.4 wt% range, where thermodynamic changes occur. The initiating factors behind this effect are supposed to be the self-assembly of quantum dots, and the distortion of the orientation order of liquid crystal molecules at a higher mass concentration of quantum dots.
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Affiliation(s)
- Alexander D Kurilov
- Prokhorov General Physics Institute of the Russian Academy of Sciences, 38 Vavilova St, Moscow, 119991, Russia.
- Moscow Region State University, 24 Very Voloshinoy St., 141014, Mytishchi, Russia
| | - Denis N Chausov
- Prokhorov General Physics Institute of the Russian Academy of Sciences, 38 Vavilova St, Moscow, 119991, Russia.
- Moscow University for Industry and Finance "Synergy", 2 Izmailovsky Val St., Moscow, 105318, Russia
| | - Valentina V Osipova
- Kazan National Research Technological University, 68 K. Marx St., 420015, Kazan, Russia
| | - Dmitriy O Sagdeev
- Kazan National Research Technological University, 68 K. Marx St., 420015, Kazan, Russia
| | - Igor S Chekulaev
- Prokhorov General Physics Institute of the Russian Academy of Sciences, 38 Vavilova St, Moscow, 119991, Russia.
- Moscow Region State University, 24 Very Voloshinoy St., 141014, Mytishchi, Russia
| | - Roman N Kucherov
- Prokhorov General Physics Institute of the Russian Academy of Sciences, 38 Vavilova St, Moscow, 119991, Russia.
- Moscow Region State University, 24 Very Voloshinoy St., 141014, Mytishchi, Russia
| | - Victor V Belyaev
- Moscow Region State University, 24 Very Voloshinoy St., 141014, Mytishchi, Russia
| | - Yuriy G Galyametdinov
- Kazan National Research Technological University, 68 K. Marx St., 420015, Kazan, Russia
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Mukherjee PK. Smectic-A to chiral smectic-C∗ phase transition in the mixture of ferroelectric liquid crystal and ferromagnetic nanoparticles. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.117839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Influence of ZnO nanoparticles on the polarization, dielectric and electro-optic behaviour in the smectic C* and hexatic I* phases. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2018.11.100] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Kyrou C, Kralj S, Panagopoulou M, Raptis Y, Nounesis G, Lelidis I. Impact of spherical nanoparticles on nematic order parameters. Phys Rev E 2018; 97:042701. [PMID: 29758630 DOI: 10.1103/physreve.97.042701] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Indexed: 06/08/2023]
Abstract
We study experimentally the impact of spherical nanoparticles on the orientational order parameters of a host nematic liquid crystal. We use spherical core-shell quantum dots that are surface functionalized to promote homeotropic anchoring on their interface with the liquid crystal host. We show experimentally that the orientational order may be strongly affected by the presence of spherical nanoparticles even at low concentrations. The orientational order of the composite system is probed by means of polarized micro-Raman spectroscopy and by optical birefringence measurements as function of temperature and concentration. Our data show that the orientational order depends on the concentration in a nonlinear way, and the existence of a crossover concentration χ_{c}≈0.004pw. It separates two different regimes exhibiting pure-liquid crystal like (χ<χ_{c}) and distorted-nematic ordering (χ>χ_{c}), respectively. In the latter phase the degree of ordering is lower with respect to the pure-liquid crystal nematic phase.
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Affiliation(s)
- C Kyrou
- Faculty of Physics, National and Kapodistrian University of Athens, Panepistimiopolis, Zografos, Athens 157 84, Greece
| | - S Kralj
- Faculty of Natural Sciences and Mathematics, University of Maribor, 2000 Maribor, Slovenia
| | - M Panagopoulou
- Physics Department, National Technical University of Athens, Heroon Polytechniou 9, 15780 Zographou, Athens, Greece
| | - Y Raptis
- Physics Department, National Technical University of Athens, Heroon Polytechniou 9, 15780 Zographou, Athens, Greece
| | - G Nounesis
- Biomolecular Physics Laboratory, National Centre for Scientific Research Demokritos, Aghia Paraskevi, Greece
| | - I Lelidis
- Faculty of Physics, National and Kapodistrian University of Athens, Panepistimiopolis, Zografos, Athens 157 84, Greece
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Singh DP, Gupta SK, Vimal T, Manohar R. Formation of periodic domains and change in physical properties of paramagnetic copper doped ZnO nanoparticle dispersed ferroelectric liquid crystal system. J Mol Liq 2014. [DOI: 10.1016/j.molliq.2014.07.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Tovkach OM, Fukuda JI, Lev BI. Peculiarity of the interaction of small particles in smectic liquid crystals. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:052502. [PMID: 24329283 DOI: 10.1103/physreve.88.052502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 10/30/2013] [Indexed: 06/03/2023]
Abstract
We investigate the peculiarity of the interaction between particles immersed into a smectic liquid crystal with a layered structure. Such a structure of a liquid crystal imposes restrictions on possible deformations of the layer displacement field. Previous studies neglect this fact and give improper results for the interaction potential within one molecular layer. The present paper shows that such restrictions yield an interaction potential substantially different from those of previous studies. Oscillatory behavior, which was not present in the potentials of previous studies, might give rise to superstructures of immersed particles with finite interparticle distance.
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Affiliation(s)
- O M Tovkach
- Bogolyubov Institute for Theoretical Physics, NAS of Ukraine, Metrologichna 14-b, Kyiv 03680, Ukraine
| | - Jun-ichi Fukuda
- Nanosystem Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba 305-8568, Japan
| | - B I Lev
- Bogolyubov Institute for Theoretical Physics, NAS of Ukraine, Metrologichna 14-b, Kyiv 03680, Ukraine and Nanosystem Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba 305-8568, Japan
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