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721 results on '"Sokolov, Alexei P."'

107. Engineering the Interlayer Spacing by Pre‐Intercalation for High Performance Supercapacitor MXene Electrodes in Room Temperature Ionic Liquid (Adv. Funct. Mater. 33/2021)

Author

Liang, Kun, primary, Matsumoto, Ray A., additional, Zhao, Wei, additional, Osti, Naresh C., additional, Popov, Ivan, additional, Thapaliya, Bishnu P., additional, Fleischmann, Simon, additional, Misra, Sudhajit, additional, Prenger, Kaitlyn, additional, Tyagi, Madhusudan, additional, Mamontov, Eugene, additional, Augustyn, Veronica, additional, Unocic, Raymond R., additional, Sokolov, Alexei P., additional, Dai, Sheng, additional, Cummings, Peter T., additional, and Naguib, Michael, additional

Published
2021
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111. Tip-enhanced photoluminescence of monolayer MoS2increased and spectrally shifted by injection of electrons

Author

Wang, Jizhou, Han, Zehua, He, Zhe, Wang, Kai, Liu, Xiaohui, and Sokolov, Alexei V.

Abstract

Using tip-enhanced photoluminescence (TEPL), we investigate micron-size monolayer MoS2flakes. In a sequence of studies, we apply various voltages between the Ag-coated nano-tip and the MoS2flakes and observe an intriguing result. During the TEPL measurement, we observe that the photoluminescence spectrum is blue shifted and the overall signal intensity is increased. We attribute this behavior to plasmon-induced electron injection into MoS2. Additionally, when the tip is negatively biased with respect to the sample during the TEPL measurement, the nonuniform TEPL images of MoS2monolayer flakes containing defects are gradually changed to be uniform that reach saturation. We verify that this saturation state in TEPL can last over half a year.

Published
2023
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115. Investigation of Unusual Conductivity Behavior and Ion Dynamics in Hexamethylguanidinium Bis(fluorosulfonyl)imide-Based Electrolytes for Sodium Batteries

Author

Biernacka, Karolina, primary, Makhlooghiazad, Faezeh, additional, Popov, Ivan, additional, Zhu, Haijin, additional, Chotard, Jean-Noël, additional, Forsyth, Craig M., additional, Yunis, Ruhamah, additional, O’Dell, Luke A., additional, Sokolov, Alexei P., additional, Pringle, Jennifer M., additional, and Forsyth, Maria, additional

Published
2021
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124. A Rayleighian approach for modeling kinetics of ionic transport in polymeric media.

Author

Kumar, Rajeev, Mahalik, Jyoti P., Bocharova, Vera, Stacy, Eric W., Gainaru, Catalin, Tomonori Saito, Gobet, Mallory P., Greenbaum, Steve, Sumpter, Bobby G., and Sokolov, Alexei P.

Subjects
IONIC liquids, RAYLEIGH model, ANALYTICAL mechanics, ELECTRODES, NUCLEAR magnetic resonance
Abstract

We report a theoretical approach for analyzing impedance of ionic liquids (ILs) and charged polymers such as polymerized ionic liquids (PolyILs) within linear response. The approach is based on the Rayleigh dissipation function formalism, which provides a computational framework for a systematic study of various factors, including polymer dynamics, in affecting the impedance. We present an analytical expression for the impedance within linear response by constructing a one-dimensional model for ionic transport in ILs/PolyILs. This expression is used to extract mutual diffusion constants, the length scale of mutual diffusion, and thicknesses of a low-dielectric layer on the electrodes from the broadband dielectric spectroscopy measurements done for an IL and three PolyILs. Also, static dielectric permittivities of the IL and the PolyILs are determined. The extracted mutual diffusion constants are compared with the self-diffusion constants of ions measured using pulse field gradient (PFG) fluorine nuclear magnetic resonance (NMR). For the first time, excellent agreement between the diffusivities extracted from the Electrode Polarization spectra (EPS) of IL/PolyILs and those measured using the PFG-NMR are found, which allows the use of the EPS and the PFG-NMR techniques in a complimentary manner for a general understanding of the ionic transport. [ABSTRACT FROM AUTHOR]

Published
2017
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133. Bridging-Controlled Network Microstructure and Long-Wavelength Fluctuations in Silica–Poly(2-vinylpyridine) Nanocomposites: Experimental Results and Theoretical Analysis

Author

Zhou, Yuxing, primary, Yavitt, Benjamin M., additional, Zhou, Zhengping, additional, Bocharova, Vera, additional, Salatto, Daniel, additional, Endoh, Maya K., additional, Ribbe, Alexander E., additional, Sokolov, Alexei P., additional, Koga, Tadanori, additional, and Schweizer, Kenneth S., additional

Published
2020
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136. Ionic Liquid‐Directed Nanoporous TiNb 2 O 7 Anodes with Superior Performance for Fast‐Rechargeable Lithium‐Ion Batteries

Author

Tao, Runming, primary, Yang, Guang, additional, Self, Ethan C., additional, Liang, Jiyuan, additional, Dunlap, John R., additional, Men, Shuang, additional, Do‐Thanh, Chi‐Linh, additional, Liu, Jixing, additional, Zhang, Yiman, additional, Zhao, Sheng, additional, Lyu, Hailong, additional, Sokolov, Alexei P., additional, Nanda, Jagjit, additional, Sun, Xiao‐Guang, additional, and Dai, Sheng, additional

Published
2020
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140. Critical Role of Anion–Solvent Interactions for Dynamics of Solvent-in-Salt Solutions

Author

Popov, Ivan, primary, Sacci, Robert L., additional, Sanders, Nicolette C., additional, Matsumoto, Ray A., additional, Thompson, Matthew W., additional, Osti, Naresh C., additional, Kobayashi, Takeshi, additional, Tyagi, Madhusudan, additional, Mamontov, Eugene, additional, Pruski, Marek, additional, Cummings, Peter T., additional, and Sokolov, Alexei P., additional

Published
2020
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142. Addition of Short Polymer Chains Mechanically Reinforces Glassy Poly(2-vinylpyridine)–Silica Nanoparticle Nanocomposites

Author

Bocharova, Vera, primary, Genix, Anne-Caroline, additional, Carrillo, Jan-Michael Y., additional, Kumar, Rajeev, additional, Carroll, Bobby, additional, Erwin, Andrew, additional, Voylov, Dmitry, additional, Kisliuk, Alexander, additional, Wang, Yangyang, additional, Sumpter, Bobby G., additional, and Sokolov, Alexei P., additional

Published
2020
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146. Communication: Influence of nanophase segregation on ion transport in room temperature ionic liquids.

Author

Griffin, Philip J., Yangyang Wang, Holt, Adam P., and Sokolov, Alexei P.

Subjects
IONIC conductivity, SHEAR flow, VISCOSITY, IONIC liquids, QUATERNARY ammonium compounds, IMIDAZOLES
Abstract

We report measurements of the ionic conductivity, shear viscosity, and structural dynamics in a homologous series of quaternary ammonium ionic liquids (ILs) and a prototypical imidazolium-based IL over a wide range of temperatures down to the glass transition. We find that the ionic conductivity of these materials generally decreases, while the shear viscosity correspondingly increases, with increasing volume fraction of aliphatic side groups. Upon crossing an aliphatic volume fraction of ~0.40, we observe a sharp, order-of-magnitude decrease in ionic conductivity and enhancement of viscosity, which coincides with the presence of long-lived, nanometer-sized alkyl aggregates. These strong changes in dynamics are not mirrored in the ionicity of these ILs, which decreases nearly linearly with aliphatic volume fraction. Our results demonstrate that nanophase segregation in neat ILs strongly reduces ionic conductivity primarily due to an aggregation-induced suppression of dynamics. [ABSTRACT FROM AUTHOR]

Published
2016
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147. Revealing spatially heterogeneous relaxation in a model nanocomposite.

Author

Shiwang Cheng, Mirigian, Stephen, Carrillo, Jan-Michael Y., Bocharova, Vera, Sumpter, Bobby G., Schweizer, Kenneth S., and Sokolov, Alexei P.

Subjects
NANOCOMPOSITE materials, BROADBAND dielectric spectroscopy, ATOMISM, SIMULATION methods & models, NANOPARTICLES
Abstract

The detailed nature of spatially heterogeneous dynamics of glycerol-silica nanocomposites is unraveled by combining dielectric spectroscopy with atomistic simulation and statistical mechanical theory. Analysis of the spatial mobility gradient shows no "glassy" layer, but the ɑ-relaxation time near the nanoparticle grows with cooling faster than the ɑ-relaxation time in the bulk and is ~20 times longer at low temperatures. The interfacial layer thickness increases from ~1.8 nm at higher temperatures to ~3.5 nm upon cooling to near bulk Tg. A real space microscopic description of the mobility gradient is constructed by synergistically combining high temperature atomistic simulation with theory. Our analysis suggests that the interfacial slowing down arises mainly due to an increase of the local cage scale barrier for activated hopping induced by enhanced packing and densification near the nanoparticle surface. The theory is employed to predict how local surface densification can be manipulated to control layer dynamics and shear rigidity over a wide temperature range. [ABSTRACT FROM AUTHOR]

Published
2015
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148. The glass transition: new ideas in an age-old field

Author

Sokolov, Alexei P.

Subjects
Transition temperature -- Research, Condensed matter -- Research, Glass -- Analysis, Science and technology
Abstract

Despite its ubiquity and long history of investigation, the nature of the glass transition still remains one of the most interesting and puzzling unsolved problems in the physics of condensed matter. However, significant progress in this field has been achieved during the past decade. In this article new ideas formulated in this field and some of the unexpected implications of these ideas are briefly discussed.

Published
1997

149. Ion transport and structural dynamics in homologous ammonium and phosphonium-based room temperature ionic liquids.

Author

Griffin, Philip J., Holt, Adam P., Katsuhiko Tsunashima, Sangoro, Joshua R., Kremer, Friedrich, and Sokolov, Alexei P.

Subjects
STRUCTURAL dynamics, IONIC liquids, AMMONIUM, PHOSPHONIUM compounds, GLASS transition temperature, BROADBAND dielectric spectroscopy, QUASIELASTIC light scattering
Abstract

Charge transport and structural dynamics in a homologous pair of ammonium and phosphonium based room temperature ionic liquids (ILs) have been characterized over a wide temperature range using broadband dielectric spectroscopy and quasi-elastic light scattering spectroscopy. We have found that the ionic conductivity of the phosphonium based IL is significantly enhanced relative to the ammonium homolog, and this increase is primarily a result of a lower glass transition temperature and higher ion mobility. Additionally, these ILs exhibit pronounced secondary relaxations which are strongly influenced by the atomic identity of the cation charge center. While the secondary relaxation in the phosphonium IL has the expected Arrhenius temperature dependence characteristic of local beta relaxations, the corresponding relaxation process in the ammonium IL was found to exhibit a mildly non-Arrhenius temperature dependence in the measured temperature range--indicative of molecular cooperativity. These differences in both local and long-range molecular dynamics are a direct reflection of the subtly different inter-ionic interactions and mesoscale structures found in these homologous ILs. [ABSTRACT FROM AUTHOR]

Published
2015
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150. Tailored crosslinking of Poly(ethylene oxide) enables mechanical robustness and improved sodium-ion conductivity

Author

Lehmann, Michelle L., primary, Yang, Guang, additional, Gilmer, Dustin, additional, Han, Kee Sung, additional, Self, Ethan C., additional, Ruther, Rose E., additional, Ge, Sirui, additional, Li, Bingrui, additional, Murugesan, Vijayakumar, additional, Sokolov, Alexei P., additional, Delnick, Frank M., additional, Nanda, Jagjit, additional, and Saito, Tomonori, additional

Published
2019
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