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  1. Article ; Online: In situ observation of coalescence of nuclei in colloidal crystal-crystal transitions.

    Peng, Yi / Li, Wei / Still, Tim / Yodh, Arjun G / Han, Yilong

    Nature communications

    2023  Volume 14, Issue 1, Page(s) 4905

    Abstract: Coalescence of nuclei in phase transitions significantly influences the transition rate and the properties of product materials, but these processes occur rapidly and are difficult to observe at the microscopic scale. Here, we directly image the ... ...

    Abstract Coalescence of nuclei in phase transitions significantly influences the transition rate and the properties of product materials, but these processes occur rapidly and are difficult to observe at the microscopic scale. Here, we directly image the coalescence of nuclei with single particle resolution during the crystal-crystal transition from a multilayer square to triangular lattices. The coalescence process exhibits three similar stages across a variety of scenarios: coupled growth of two nuclei, their attachment, and relaxation of the coalesced nucleus. The kinetics vary with nucleus size, interface, and lattice orientation; the kinetics include acceleration of nucleus growth, small nucleus liquefaction, and generation/annihilation of defects. Related mechanisms, such as strain induced by nucleus growth and the lower energy of liquid-crystal versus crystal-crystal interfaces, appear to be common to both atomic and colloidal crystals.
    Language English
    Publishing date 2023-08-15
    Publishing country England
    Document type Journal Article
    ZDB-ID 2553671-0
    ISSN 2041-1723 ; 2041-1723
    ISSN (online) 2041-1723
    ISSN 2041-1723
    DOI 10.1038/s41467-023-40627-w
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article: Origin of the Acoustic Bandgaps in Hypersonic Colloidal Phononics: The Role of the Elastic Impedance

    Cang, Yu / Sainidou, Rebecca / Rembert, Pascal / Magnabosco, Giulia / Still, Tim / Vogel, Nicolas / Graczykowski, Bartlomiej / Fytas, George

    Journal of physical chemistry. 2022 Aug. 23, v. 126, no. 34

    2022  

    Abstract: How phonons propagate in nanostructures determines the flow of elastic and thermal energy in dielectric materials. However, a reliable theoretical prediction of the phonon dispersion relation requires experimental verification both near to and far from ... ...

    Abstract How phonons propagate in nanostructures determines the flow of elastic and thermal energy in dielectric materials. However, a reliable theoretical prediction of the phonon dispersion relation requires experimental verification both near to and far from the Brillouin zone of the nanostructure. We report on the experimental hypersonic phonon dispersion of hard (SiO₂) and soft (polymer) fcc colloidal crystals infiltrated in liquid polydimethylsiloxane with different elastic impedance contrast using Brillouin light spectroscopy. We discuss the distinct differences with first-principles full elastodynamic calculations involving a multiple-scattering theory. Interparticle contacts strongly impact the long-wavelength speed of sound and the nature of the particle vibration resonance-induced hybridization hypersonic bandgap. The absence of the order-induced Bragg bandgap in SiO₂ and its presence in soft opals cannot be fully accounted for by the theory, limiting its predictive power. Bridging the elasticity of the two colloidal crystals with suitable SiO₂ core–shell (polymer) particles reveals an unprecedented crossover behavior in the dispersion relation. In view of many conversational parameters, the control tuning of phonon propagation in soft matter-based hypersonic phononics remains challenging.
    Keywords acoustics ; hybridization ; liquids ; nanomaterials ; physical chemistry ; polydimethylsiloxane ; prediction ; spectroscopy ; thermal energy ; vibration
    Language English
    Dates of publication 2022-0823
    Size p. 6575-6584.
    Publishing place American Chemical Society
    Document type Article
    ISSN 1520-5207
    DOI 10.1021/acs.jpcb.2c03923
    Database NAL-Catalogue (AGRICOLA)

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  3. Article ; Online: Origin of the Acoustic Bandgaps in Hypersonic Colloidal Phononics: The Role of the Elastic Impedance.

    Cang, Yu / Sainidou, Rebecca / Rembert, Pascal / Magnabosco, Giulia / Still, Tim / Vogel, Nicolas / Graczykowski, Bartlomiej / Fytas, George

    The journal of physical chemistry. B

    2022  Volume 126, Issue 34, Page(s) 6575–6584

    Abstract: How phonons propagate in nanostructures determines the flow of elastic and thermal energy in dielectric materials. However, a reliable theoretical prediction of the phonon dispersion relation requires experimental verification both near to and far from ... ...

    Abstract How phonons propagate in nanostructures determines the flow of elastic and thermal energy in dielectric materials. However, a reliable theoretical prediction of the phonon dispersion relation requires experimental verification both near to and far from the Brillouin zone of the nanostructure. We report on the experimental hypersonic phonon dispersion of hard (SiO
    Language English
    Publishing date 2022-08-23
    Publishing country United States
    Document type Journal Article
    ISSN 1520-5207
    ISSN (online) 1520-5207
    DOI 10.1021/acs.jpcb.2c03923
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Shear-assisted grain coarsening in colloidal polycrystals.

    Li, Wei / Peng, Yi / Zhang, Yongjun / Still, Tim / Yodh, A G / Han, Yilong

    Proceedings of the National Academy of Sciences of the United States of America

    2020  Volume 117, Issue 39, Page(s) 24055–24060

    Abstract: Grain growth under shear annealing is crucial for controlling the properties of polycrystalline materials. However, their microscopic kinetics are not well understood because individual atomic trajectories are difficult to track. Here, we study grain ... ...

    Abstract Grain growth under shear annealing is crucial for controlling the properties of polycrystalline materials. However, their microscopic kinetics are not well understood because individual atomic trajectories are difficult to track. Here, we study grain growth with single-particle kinetics in colloidal polycrystals using video microscopy. Rich grain-growth phenomena are revealed in three shear regimes, including the normal grain growth (NGG) in weak shear melting-recrystallization process in strong shear. For intermediate shear, early stage NGG is arrested by built-up stress and eventually gives way to dynamic abnormal grain growth (DAGG). We find that DAGG occurs via a melting-recrystallization process, which naturally explains the puzzling stress drop at the onset of DAGG in metals. Moreover, we visualize that grain boundary (GB) migration is coupled with shear via disconnection gliding. The disconnection-gliding dynamics and the collective motions of ambient particles are resolved. We also observed that grain rotation can violate the conventional relation [Formula: see text] (R is the grain radius, and θ is the misorientation angle between two grains) by emission and annihilation of dislocations across the grain, resulting in a step-by-step rotation. Besides grain growth, we discover a result in shear-induced melting: The melting volume fraction varies sinusoidally on the angle mismatch between the triangular lattice orientation of the grain and the shear direction. These discoveries hold potential to inform microstructure engineering of polycrystalline materials.
    Language English
    Publishing date 2020-09-16
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 209104-5
    ISSN 1091-6490 ; 0027-8424
    ISSN (online) 1091-6490
    ISSN 0027-8424
    DOI 10.1073/pnas.2013456117
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Cologne/Königswinter

    Zs.A 1148: Show issues Location:
    Je nach Verfügbarkeit (siehe Angabe bei Bestand)
    bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
    Jg. 1995 - 2021: Lesesall (1.OG)
    ab Jg. 2022: Lesesaal (EG)

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  5. Book ; Online ; Thesis: High Frequency Acoustics in Colloid-Based Meso- and Nanostructures by Spontaneous Brillouin Light Scattering

    Still, Tim

    (Springer Theses)

    2010  

    Abstract: The present thesis deals with the exploration of phononic properties ofmeso- and nanostructured colloid-based composite materials at hypersonic(GHz) frequencies. The emerging field of phononics, the mechanical analogue of photonics, treats the ... ...

    Author's details by Tim Still
    Series title Springer Theses
    Abstract The present thesis deals with the exploration of phononic properties ofmeso- and nanostructured colloid-based composite materials at hypersonic(GHz) frequencies. The emerging field of phononics, the mechanical analogue of photonics, treats the propagation and manipulation of acoustic waves in structured materials. Due to their widely tunable properties (size, density, etc.) and their ability to self-assembly, polymer colloids are ideal systems to realize hypersonic phononics, which are investigated by Brillouin light scattering herein. Therefore, both the mechanical and physical properties of the individual colloidal particles, which manifest in their resonance vibrations (eigenmodes), as well as the acoustic propagation in colloidal structures have been investigated.This thesis already lead to several journal publications and seven presentations at international conferences, and was honored summa cum laude.
    Keywords Acoustics ; Chemistry ; Nanotechnology ; Polymers ; Surfaces (Physics) ; Technik / Wissen Chemie
    Language English
    Size Online-Ressource, v.: digital
    Publisher Springer-Verlag Berlin Heidelberg
    Publishing place Berlin, Heidelberg
    Document type Book ; Online ; Thesis
    Thesis / German Habilitation thesis Univ., Diss.--Mainz, 2009
    Note "Doctoral thesis performed at Max Planck Institute for Polymer Research and accepted by Johannes Gutenberg University, Mainz, Germany ; Includes bibliographical references and index
    ISBN 9783642134821 ; 9783642134838 ; 3642134823 ; 3642134831
    DOI 10.1007/978-3-642-13483-8
    Database Library catalogue of the German National Library of Science and Technology (TIB), Hannover

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  6. Book ; Thesis: High frequency acoustics in colloid-based meso- and nanostructures by spontaneous Brillouin light scattering

    Still, Tim

    doctoral thesis performed at Max Planck Institute for polymer research and accepted by Johannes Gutenberg University, Mainz, Germany

    (Springer theses)

    2010  

    Author's details Tim Still
    Series title Springer theses
    Keywords Elastische Welle ; Brillouin-Streuung ; Gigahertzbereich ; Kolloides System ; Phononischer Kristall
    Language English
    Size XX, 144 S., Ill., graph. Darst, 24 cm
    Publisher Springer
    Publishing place Heidelberg u.a.
    Document type Book ; Thesis
    Thesis / German Habilitation thesis Univ., Diss.--Mainz, 2009
    ISBN 9783642134821 ; 9783642134838 ; 3642134823 ; 3642134831
    Database Library catalogue of the German National Library of Science and Technology (TIB), Hannover

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  7. Book ; Online ; Thesis: High frequency acoustics in colloid-based meso- and nanostructures by spontaneous Brillouin light scattering

    Still, Tim

    2009  

    Author's details vorgelegt von Tim Still
    Language English
    Size Online-Ressource
    Document type Book ; Online ; Thesis
    Thesis / German Habilitation thesis Univ., Diss.--Mainz, 2009
    Database Library catalogue of the German National Library of Science and Technology (TIB), Hannover

    Full text online

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  8. Article ; Online: Heterogeneous Activation, Local Structure, and Softness in Supercooled Colloidal Liquids.

    Ma, Xiaoguang / Davidson, Zoey S / Still, Tim / Ivancic, Robert J S / Schoenholz, S S / Liu, A J / Yodh, A G

    Physical review letters

    2019  Volume 122, Issue 2, Page(s) 28001

    Abstract: We experimentally characterize heterogeneous nonexponential relaxation in bidisperse supercooled colloidal liquids utilizing a recent concept called "softness" [Phys. Rev. Lett. 114, 108001 (2015)PRLTAO0031-900710.1103/PhysRevLett.114.108001]. Particle ... ...

    Abstract We experimentally characterize heterogeneous nonexponential relaxation in bidisperse supercooled colloidal liquids utilizing a recent concept called "softness" [Phys. Rev. Lett. 114, 108001 (2015)PRLTAO0031-900710.1103/PhysRevLett.114.108001]. Particle trajectory and structure data enable classification of particles into subgroups with different local environments and propensities to hop. We determine residence times t_{R} between particle hops and show that t_{R} derived from particles in the same softness subgroup are exponentially distributed. Using the mean residence time t[over ¯]_{R} for each softness subgroup, and a Kramers' reaction rate model, we estimate the activation energy barriers E_{b} for particle hops, and show that both t[over ¯]_{R} and E_{b} are monotonic functions of softness. Finally, we derive information about the combinations of large and small particle neighbors that determine particle softness, and we explicitly show that multiple exponential relaxation channels in the supercooled liquid give rise to its nonexponential behavior.
    Language English
    Publishing date 2019-02-15
    Publishing country United States
    Document type Journal Article
    ZDB-ID 208853-8
    ISSN 1079-7114 ; 0031-9007
    ISSN (online) 1079-7114
    ISSN 0031-9007
    DOI 10.1103/PhysRevLett.122.028001
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Bonn / Germany

    Z 4' 58/153: Show issues

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  9. Article ; Online: Diffusive and martensitic nucleation kinetics in solid-solid transitions of colloidal crystals.

    Peng, Yi / Li, Wei / Wang, Feng / Still, Tim / Yodh, Arjun G / Han, Yilong

    Nature communications

    2017  Volume 8, Page(s) 14978

    Abstract: Solid-solid transitions between crystals follow diffusive nucleation, or various diffusionless transitions, but these kinetics are difficult to predict and observe. Here we observed the rich kinetics of transitions from square lattices to triangular ... ...

    Abstract Solid-solid transitions between crystals follow diffusive nucleation, or various diffusionless transitions, but these kinetics are difficult to predict and observe. Here we observed the rich kinetics of transitions from square lattices to triangular lattices in tunable colloidal thin films with single-particle dynamics by video microscopy. Applying a small pressure gradient in defect-free regions or near dislocations markedly transform the diffusive nucleation with an intermediate-stage liquid into a martensitic generation and oscillation of dislocation pairs followed by a diffusive nucleus growth. This transformation is neither purely diffusive nor purely martensitic as conventionally assumed but a combination thereof, and thus presents new challenges to both theory and the empirical criterion of martensitic transformations. We studied how pressure, density, grain boundary, triple junction and interface coherency affect the nucleus growth, shape and kinetic pathways. These novel microscopic kinetics cast new light on control solid-solid transitions and microstructural evolutions in polycrystals.
    Language English
    Publishing date 2017-05-15
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 2041-1723
    ISSN (online) 2041-1723
    DOI 10.1038/ncomms14978
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article ; Online: Surfactant-induced Marangoni eddies alter the coffee-rings of evaporating colloidal drops.

    Still, Tim / Yunker, Peter J / Yodh, Arjun G

    Langmuir : the ACS journal of surfaces and colloids

    2012  Volume 28, Issue 11, Page(s) 4984–4988

    Abstract: The influence of the small ionic surfactant sodium dodecyl sulfate (SDS) on the evaporation of drying colloidal droplets is quantitatively investigated. The addition of SDS leads to a significantly more uniform deposition of colloidal particles after ... ...

    Abstract The influence of the small ionic surfactant sodium dodecyl sulfate (SDS) on the evaporation of drying colloidal droplets is quantitatively investigated. The addition of SDS leads to a significantly more uniform deposition of colloidal particles after evaporation (i.e., the so-called "coffee-ring effect" is dramatically altered). We understand this phenomenon in the context of circulating radial Marangoni flows induced by the variation of SDS concentration along the air-water interface. Video microscopy permits the direct visualization of the colloidal particles involved in these flows, revealing a surprisingly stable "Marangoni eddy" that prevents particle deposition at the drop perimeter.
    Language English
    Publishing date 2012-03-20
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2005937-1
    ISSN 1520-5827 ; 0743-7463
    ISSN (online) 1520-5827
    ISSN 0743-7463
    DOI 10.1021/la204928m
    Database MEDical Literature Analysis and Retrieval System OnLINE

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