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Sidebottom DL. Generic α relaxation in a strong GeO_{2} glass melt. Phys Rev E 2023; 107:L012602. [PMID: 36797860 DOI: 10.1103/physreve.107.l012602] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Accepted: 01/09/2023] [Indexed: 06/18/2023]
Abstract
The viscoelastic α relaxation in glass-forming GeO_{2} was measured over a range of temperatures near the glass transition using photon correlation spectroscopy. The relaxation in this "strong" glass former exhibits a nonexponential decay identical to that found in a great many simple organic "fragile" liquids. This finding contradicts the longstanding conjecture that nonexponentiality of viscous relaxations near the glass transition are correlated to the liquid's fragility. Instead, the findings offer support for a recent proposal that the nonexponentiality parameter of the α-relaxation in supercooled liquids displays a universal value β(T_{g})=1/2 near the glass transition.
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Affiliation(s)
- D L Sidebottom
- Department of Physics, Creighton University, 2500 California Plaza, Omaha, NE 68178, USA
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Griffin PJ, Agapov AL, Sokolov AP. Translation-rotation decoupling and nonexponentiality in room temperature ionic liquids. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 86:021508. [PMID: 23005770 DOI: 10.1103/physreve.86.021508] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Indexed: 06/01/2023]
Abstract
Using a combination of light scattering techniques and broadband dielectric spectroscopy, we have measured the temperature dependence of structural relaxation time and self diffusion in three imidazolium-based room temperature ionic liquids: [bmim][NTf(2)], [bmim][PF(6)], and [bmim][TFA]. A detailed analysis of the results demonstrates that self diffusion decouples from structural relaxation in these systems as the temperature is decreased toward T(g). The degree to which the dynamics are decoupled, however, is shown to be surprisingly weak when compared to other supercooled liquids of similar fragility. In addition to the weak decoupling, we demonstrate that the temperature dependence of the structural relaxation time in all three liquids can be well described by a single Vogel-Fulcher-Tamann function over 13 decades in time from 10(-11) s up to 10(2) s. Furthermore, the stretching of the structural relaxation is shown to be temperature independent over the same range of time scales, i.e., time temperature superposition is valid for these ionic liquids from far above the melting point down to the glass transition temperature. We suggest that these phenomena are interconnected and all result from the same underlying mechanism--strong and directional intermolecular interactions.
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Affiliation(s)
- Philip J Griffin
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996-1600, USA
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Wang L, Li J, Fecht HJ. Correlating the stretched-exponential and super-Arrhenius behaviors in the structural relaxation of glass-forming liquids. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:155102. [PMID: 21436503 DOI: 10.1088/0953-8984/23/15/155102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Following the report of a single-exponential activation behavior behind the super-Arrhenius structural relaxation of glass-forming liquids in our preceding paper, we find that the non-exponentiality in the structural relaxation of glass-forming liquids is straightforwardly determined by the relaxation time, and could be calculated from the measured relaxation data. Comparisons between the calculated and measured non-exponentialities for typical glass-forming liquids, from fragile to intermediate, convincingly support the present analysis. Hence the origin of the non-exponentiality and its correlation with liquid fragility become clearer.
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Affiliation(s)
- Lianwen Wang
- Institute of Materials Science and Engineering, Lanzhou University, Lanzhou 730000, People's Republic of China.
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Abstract
AbstractIn the light of the strong and fragile classification of simple liquids we review some of the relaxation data for some well-known polymers to see the extent to which a similar pattern may be manifested. Relaxation time data rather than viscosity data are used in the polymer case to avoid complications from long chain effects on the Vogel-Fulcher equation pre exponent. A combination of light scattering and 13C NMR data seem to provide the most reliable guide to the microviscosity of interest to the classification. A pattern similar to that for viscous liquids is recovered with polyisobutylene, the “strongest” chain polymer and bisphenol polycarbonate, the most fragile. The extent to which correlations of other properties with fragility, found in the non-polymeric liquids cases, will carry over to the polymer case is still being evaluated, though the work of Hodge on the analysis of the more complicated problem of non-linear thermal relaxation, suggests the carry over may be extensive.
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Yang Y, Muller LJ, Nelson KA. Relaxational Dynamics and Strength in Supercooled Liquids from Impulsive Stimulated Thermal Scattering. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-407-145] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTImpulsive stimulated thermal scattering (ISTS), a time-domain light scattering technique, provides a more than 6-decade time range from sub-ns to many ms. It permits characterization of the structural relaxation dynamics and determination of the relaxation strength or Debye-Waller factor in supercooled liquids, and thus allows testing of the mode coupling theory of the liquidglass transition. ISTS experiments were performed on glass formers salol, butylbenzene, and the molten salt [Ca(N03)]0.4[KNO3]0.6. The relaxational dynamics and the Debye-Waller factorfq=0 were obtained. A square-root anomaly was observed in fq=0 (T) at a crossover temperature Tc for all three materials, consistent with the prediction of mode coupling theory.
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Colby RH. Dynamic scaling approach to glass formation. PHYSICAL REVIEW. E, STATISTICAL PHYSICS, PLASMAS, FLUIDS, AND RELATED INTERDISCIPLINARY TOPICS 2000; 61:1783-1792. [PMID: 11046462 DOI: 10.1103/physreve.61.1783] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/1999] [Indexed: 05/23/2023]
Abstract
Experimental data for the temperature dependence of relaxation times are used to argue that the dynamic scaling form, with relaxation time diverging at the critical temperature T(c) as (T-T(c))(-nuz), is superior to the classical Vogel form. This observation leads us to propose that glass formation can be described by a simple mean-field limit of a phase transition. The order parameter is the fraction of all space that has sufficient free volume to allow substantial motion, and grows logarithmically above T(c). Diffusion of this free volume creates random walk clusters that have cooperatively rearranged. We show that the distribution of cooperatively moving clusters must have a Fisher exponent tau=2. Dynamic scaling predicts a power law for the relaxation modulus G(t) approximately t(-2/z), where z is the dynamic critical exponent relating the relaxation time of a cluster to its size. Andrade creep, universally observed for all glass-forming materials, suggests z=6. Experimental data on the temperature dependence of viscosity and relaxation time of glass-forming liquids suggest that the exponent nu describing the correlation length divergence in this simple scaling picture is not always universal. Polymers appear to universally have nuz=9 (making nu=3 / 2). However, other glass-formers have unphysically large values of nuz, suggesting that the availability of free volume is a necessary, but not sufficient, condition for motion in these liquids. Such considerations lead us to assert that nuz=9 is in fact universal for all glass- forming liquids, but an energetic barrier to motion must also be overcome for strong glasses.
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Affiliation(s)
- RH Colby
- Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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Di Biasio A. Relaxation phenomena in sol–gel transition. Colloids Surf A Physicochem Eng Asp 1998. [DOI: 10.1016/s0927-7757(97)00285-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Pavlatou EA, Yannopoulos SN, Papatheodorou GN, Fytas G. Dynamics of Density and Orientation Fluctuations in Supercooled Zinc Halides. J Phys Chem B 1997. [DOI: 10.1021/jp970343s] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- E. A. Pavlatou
- Institute of Chemical Engineering and High Temperature Chemical Processes and Department of Chemical Engineering, University of Patras, P.O. Box 1414, GR-26500 Patras, Greece
| | - S. N. Yannopoulos
- Institute of Chemical Engineering and High Temperature Chemical Processes and Department of Chemical Engineering, University of Patras, P.O. Box 1414, GR-26500 Patras, Greece
| | - G. N. Papatheodorou
- Institute of Chemical Engineering and High Temperature Chemical Processes and Department of Chemical Engineering, University of Patras, P.O. Box 1414, GR-26500 Patras, Greece
| | - G. Fytas
- Institute of Electronic Structure and Laser, P.O. Box 1527, GR-711 10 Heraklion, Crete, Greece
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Pimenov A, Lunkenheimer P, Rall H, Kohlhaas R, Loidl A, Böhmer R. Ion transport in the fragile glass former 3KNO3-2Ca(NO3)2. PHYSICAL REVIEW. E, STATISTICAL PHYSICS, PLASMAS, FLUIDS, AND RELATED INTERDISCIPLINARY TOPICS 1996; 54:676-684. [PMID: 9965115 DOI: 10.1103/physreve.54.676] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Yang Y, Nelson KA. Impulsive stimulated thermal scattering study of α relaxation dynamics and the Debye–Waller factor anomaly in Ca0.4K0.6(NO3)1.4. J Chem Phys 1996. [DOI: 10.1063/1.471782] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Li G, Du WM, Hernandez J, Cummins HZ. Locating the nonergodicity-parameter anomaly near the liquid-to-glass crossover temperature in CaKNO3 by Brillouin scattering. PHYSICAL REVIEW. E, STATISTICAL PHYSICS, PLASMAS, FLUIDS, AND RELATED INTERDISCIPLINARY TOPICS 1993; 48:1192-1206. [PMID: 9960705 DOI: 10.1103/physreve.48.1192] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Tao NJ, Li G, Cummins HZ. Brillouin-scattering study of the liquid-glass transition in CaKNO3: Mode-coupling analysis. PHYSICAL REVIEW. B, CONDENSED MATTER 1992; 45:686-696. [PMID: 10001108 DOI: 10.1103/physrevb.45.686] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Tao NJ, Li G, Cummins HZ. Self-similar light-scattering spectra of beta relaxation near the liquid-glass transition. PHYSICAL REVIEW LETTERS 1991; 66:1334-1337. [PMID: 10043179 DOI: 10.1103/physrevlett.66.1334] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Pavlatou EA, Rizos AK, Papatheodorou GN, Fytas G. Dynamic light scattering study of ionic KNO3–Ca(NO3)2mixtures. J Chem Phys 1991. [DOI: 10.1063/1.460731] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Floudas G, Fytas G, Alig I. Brillouin scattering from bulk polybutadiene: distribution of relaxation times versus single relaxation time approach. POLYMER 1991. [DOI: 10.1016/0032-3861(91)90065-q] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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