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Flores-Ruiz H, Micoulaut M. Crucial Role of S8-Rings in Structural, Relaxation, Vibrational and Electronic Properties of LiquidSulfur close to the λ Transition. J Chem Phys 2022; 157:054507. [DOI: 10.1063/5.0090953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Liquid sulfur has been studied by density-functional based molecular-dynamics simulations at different temperatures ranging from 400 K up to 700 K across the well-documented λ-transition. Structure models containing either a majority of Sn chains or S8 rings are considered and compared to experimental data from X-ray scattering. The comparison suggests a liquid structure of a majority of 2-fold sulfur at low temperature, dominated by S8 rings that open progressively upon temperature increase. Typical features associated with such rings are analyzed and indicate that they contribute to a specific third correlating distance in the pair correlation function and to a contribution at low wavevector k in reciprocal space. The vibrational properties of liquid sulfur are also considered and indicate a contribution at 60 meV that is associated with both chains and rings, albeit the latter lead to a more intense peak at this wavenumber. The underlying network structure also impacts the dynamic properties of the melts which display enhanced dynamic heterogeneities when S8 rings are present. The analysis of the electronic Kohn-Sham energies shows insulating character with a gap of about ≃2.0 eV, albeit the presence of localized mid-gap states is acknowledged that can be associated, in part, with the presence of S6rings.
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Affiliation(s)
- Hugo Flores-Ruiz
- Universidad de Guadalajara - Centro Universitario de Valles, Mexico
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Zhang H, Wang X, Yu HB, Douglas JF. Dynamic heterogeneity, cooperative motion, and Johari-Goldstein [Formula: see text]-relaxation in a metallic glass-forming material exhibiting a fragile-to-strong transition. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2021; 44:56. [PMID: 33871722 DOI: 10.1140/epje/s10189-021-00060-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 03/21/2021] [Indexed: 06/12/2023]
Abstract
We investigate the Johari-Goldstein (JG) [Formula: see text]-relaxation process in a model metallic glass-forming (GF) material ([Formula: see text]), previously studied extensively by both frequency-dependent mechanical measurements and simulation studies devoted to equilibrium properties, by molecular dynamics simulations based on validated and optimized interatomic potentials with the primary aim of better understanding the nature of this universal relaxation process from a dynamic heterogeneity (DH) perspective. The present relatively low temperature and long-time simulations reveal a direct correspondence between the JG [Formula: see text]-relaxation time [Formula: see text] and the lifetime of the mobile particle clusters [Formula: see text], defined as in previous DH studies, a relationship dual to the corresponding previously observed relationship between the [Formula: see text]-relaxation time [Formula: see text] and the lifetime of immobile particle clusters [Formula: see text]. Moreover, we find that the average diffusion coefficient D nearly coincides with [Formula: see text] of the smaller atomic species (Al) and that the 'hopping time' associated with D coincides with [Formula: see text] to within numerical uncertainty, both trends being in accord with experimental studies. This indicates that the JG [Formula: see text]-relaxation is dominated by the smaller atomic species and the observation of a direct relation between this relaxation process and rate of molecular diffusion in GF materials at low temperatures where the JG [Formula: see text]-relaxation becomes the prevalent mode of structural relaxation. As an unanticipated aspect of our study, we find that [Formula: see text] exhibits fragile-to-strong (FS) glass formation, as found in many other metallic GF liquids, but this fact does not greatly alter the geometrical nature of DH in this material and the relation of DH to dynamical properties. On the other hand, the temperature dependence of the DH and dynamical properties, such as the structural relaxation time, can be significantly altered from 'ordinary' GF liquids.
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Affiliation(s)
- Hao Zhang
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta, T6G 1H9, Canada.
| | - Xinyi Wang
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta, T6G 1H9, Canada
| | - Hai-Bin Yu
- Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, Hubei, China
| | - Jack F Douglas
- Material Measurement Laboratory, Materials Science and Engineering Division, National Institute of Standards and Technology(NIST), Gaithersburg, MD, 20899, USA.
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Gkourmpis T, Mitchell GR. The Use of Scattering Data in the Study of the Molecular Organisation of Polymers in the Non-Crystalline State. Polymers (Basel) 2020; 12:polym12122917. [PMID: 33291414 PMCID: PMC7762082 DOI: 10.3390/polym12122917] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 12/02/2020] [Accepted: 12/03/2020] [Indexed: 11/28/2022] Open
Abstract
Scattering data for polymers in the non-crystalline state, i.e., the glassy state or the molten state, may appear to contain little information. In this work, we review recent developments in the use of scattering data to evaluate in a quantitative manner the molecular organization of such polymer systems. The focus is on the local structure of chain segments, on the details of the chain conformation and on the imprint the inherent chemical connectivity has on this structure. We show the value of tightly coupling the scattering data to atomistic-level computer models. We show how quantitative information about the details of the chain conformation can be obtained directly using a model built from definitions of relatively few parameters. We show how scattering data may be supplemented with data from specific deuteration sites and used to obtain information hidden in the data. Finally, we show how we can exploit the reverse Monte Carlo approach to use the data to drive the convergence of the scattering calculated from a 3d atomistic-level model with the experimental data. We highlight the importance of the quality of the scattering data and the value in using broad Q scattering data obtained using neutrons. We illustrate these various methods with results drawn from a diverse range of polymers.
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Affiliation(s)
- Thomas Gkourmpis
- Innovation & Technology, Borealis AB, SE-444 86 Stenungsund, Sweden
- Correspondence: ; Tel.: +46-303-205-576
| | - Geoffrey R. Mitchell
- Centre of Rapid and Sustainable Product Development, Polytechnic of Leiria, 2430-028 Marinha Grande, Portugal;
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Self-healing effects in a semi-ordered liquid for stable electronic conversion of high-energy radiation. Sci Rep 2018; 8:12404. [PMID: 30120389 PMCID: PMC6098062 DOI: 10.1038/s41598-018-30815-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 08/03/2018] [Indexed: 11/08/2022] Open
Abstract
Radiation damage in solid-state semiconductors has, until now, placed strict limitations on the acceptable decay energies of radioisotopes in radiovoltaic cells. Relegation to low-energy beta-emitting isotopes has minimized the power output from these devices and limited the technology's ability to deliver greater energy densities and longer lifetimes than conventional batteries. We demonstrate the self-healing abilities of a liquid-phase semiconducting alloy which can withstand high-energy alpha radiation. Neutron diffraction of liquid selenium-sulfur shows the liquid phase repairing damage sustained in the irradiation of the solid phase. This self-healing behavior results in long-lived power output in a liquid selenium-sulfur alphavoltaic cell. To the best of our knowledge, this marks the only successful demonstration of resistance to high-energy radiation (>500 keV) in a semiconducting material. This new robustness can potentially allow increases to the available energy density in radiovoltaic cells near 1000 times the current state of the art.
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Plašienka D, Cifra P, Martoňák R. Structural transformation between long and short-chain form of liquid sulfur from ab initio molecular dynamics. J Chem Phys 2015; 142:154502. [DOI: 10.1063/1.4917040] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Dušan Plašienka
- Department of Experimental Physics, Comenius University, Mlynská Dolina F2, 842 48 Bratislava, Slovakia
| | - Peter Cifra
- Polymer Institute, Slovak Academy of Sciences, Dúbravská cesta 9, 845 41 Bratislava, Slovakia
| | - Roman Martoňák
- Department of Experimental Physics, Comenius University, Mlynská Dolina F2, 842 48 Bratislava, Slovakia
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Oligschleger C, Facius C, Kutz H, Langen C, Thumm M, von Brühl S, Wang S, Weber L, Zischler J. Molecular dynamics simulation of structural and dynamic properties of selenium structures with different degrees of amorphization. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:405402. [PMID: 21832412 DOI: 10.1088/0953-8984/21/40/405402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We investigated Se structures of different degrees of disorder ranging from a 5% up to a 95% degree of amorphization. Starting from a trigonal crystalline structure we applied different strategies to introduce disorder into the Se configurations by irradiating atoms from their crystalline equilibrium positions. According to the symmetry of the trigonal phase, we introduced three types of disorder, i.e. the first type where only atoms forming layers of complete helical chains are shifted from their original positions (the thickness of these layers is chosen to represent the chosen degree of amorphicity), the second type where only atoms in planes-of respective thicknesses-lying perpendicular to the chains are displaced and the third type where only randomly chosen atoms are shifted from their crystalline equilibrium positions. After a thermal treatment of these disordered starting configurations, we calculated structural and dynamic properties (i.e. pair-correlation function and vibrational spectrum) and compared the results to both the original crystalline data and results obtained from corresponding glass structures.
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Affiliation(s)
- C Oligschleger
- FB Angewandte Naturwissenschaften, HS Bonn-Rhein-Sieg, von-Liebig-Straße 20, 53359 Rheinbach, Germany
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Nakamura K, Tsuneyuki S. Effect of through-space electron transfer on infrared spectrum of amorphous selenium. J Chem Phys 2005; 122:194503. [PMID: 16161593 DOI: 10.1063/1.1898217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In this paper we present theoretical analyses on an infrared (IR) spectrum of amorphous selenium. The system is described by a 216-atom-chain model, and a set of molecular-dynamics simulations is performed to generate vitreous structures and vibrational modes. To describe an electronic structure of the system we employ a complete neglect of differential overlap model parametrized by ab initio cluster calculations. An IR intensity is evaluated with the Berry-phase formula for an electronic polarization. The effect of the through-space electron transfer on the IR spectrum is studied by artificially changing the magnitude of matrix elements associated with the electron transfer between nonbonded atoms in the chain. We find that the through-space electron transfer leads to (i) the enhancement of the bending IR peak at 135 cm(-1) and (ii) the appearance of a new low-frequency peak around 50 cm(-1), thus resulting in a good agreement with the experiment. The mechanism is discussed by a simple dipole model.
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Affiliation(s)
- Kazuma Nakamura
- Department of Physics, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 133-0033, Japan.
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Yannopoulos SN, Andrikopoulos KS. Raman scattering study on structural and dynamical features of noncrystalline selenium. J Chem Phys 2004; 121:4747-58. [PMID: 15332909 DOI: 10.1063/1.1780151] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We report on a detailed, temperature-dependent, off-resonant Raman scattering study of glassy and supercooled selenium. Raman spectra in the frequency regime of the first-order scattering (5-450 cm(-1)) have been recorded over a wide temperature range, i.e., 143-353 K. To facilitate the analysis, the spectra have intuitively been divided in three spectral regions. The analysis of the high frequency region (bond-stretching vibrational modes) yielded information on the rings-chains equilibrium. In particular, the polymer content was found to amount to more than 85% around the glass transition temperature, exhibiting a weak temperature dependence, which extrapolates nicely to the high-temperature dissolution data. The intermediate frequency range (representative of the medium-range structural order) was treated together with the low frequency regime (where low-energy excitations, i.e., the quasielastic line and the Boson peak are the dominant contributions) owing to their strong overlap. The study of the bond-bending regime revealed information which made it possible to clarify the role of ringlike and chainlike fragments incorporated in polymeric molecules. The temperature evolution of the Boson peak and the frequency dependence of the Raman coupling coefficient Comega were also determined. An attempt to decompose the partial contribution of the pure Boson peak to Comega revealed valuable information concerning the limiting (omega-->0) behavior of the coupling coefficient.
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Affiliation(s)
- S N Yannopoulos
- Foundation for Research and Technology Hellas--Institute of Chemical Engineering and High Temperature Chemical Processes (FORTH--ICE/HT), P.O. Box 1414, GR-26504 Patras, Greece.
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Bichara C. Competing Topological and Chemical Orders in Liquid Selenium Tellurium Alloys. MOLECULAR SIMULATION 1997. [DOI: 10.1080/08927029708024171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Oligschleger C, Jones RO, Reimann SM, Schober HR. Model interatomic potential for simulations in selenium. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 53:6165-6173. [PMID: 9982015 DOI: 10.1103/physrevb.53.6165] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Bichara C, Raty J, Gaspard J. Structure and bonding in liquid tellurium. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 53:206-211. [PMID: 9981965 DOI: 10.1103/physrevb.53.206] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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