Beyond simple exponential correlation functions and equilibrium dynamics in x-ray photon correlation spectroscopy

Madsen, Anders; Leheny, Robert L.; Guo, Hongyu; Sprung, Michael; Czakkel, Orsolya

doi:10.1088/1367-2630/12/5/055001

Cited by 179 publications

(216 citation statements)

References 73 publications

(96 reference statements)

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“…We find that the decay of the density fluctuations can be well described by compressed, thus faster than exponential correlation functions, suggesting a peculiar origin for the atomic dynamics. 27,31 This behavior seems to be universal in metallic glasses 23,24 and cannot be explained by the well-known theories for glasses dynamics, which predict a stretched exponential shape of the correlation functions, even in the glassy state. [36][37][38] Model systems such as hard spheres and Lennard-Jones are unable to reproduce these intriguing dynamic effects.…”

Section: Discussionmentioning

confidence: 90%

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Compressed correlation functions and fast aging dynamics in metallic glasses

Ruta

Baldi²,

Monaco

et al. 2013

The Journal of Chemical Physics

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We present x-ray photon correlation spectroscopy measurements of the atomic dynamics in a Zr 67 Ni 33 metallic glass, well below its glass transition temperature. We find that the decay of the density fluctuations can be well described by compressed, thus faster than exponential, correlation functions which can be modeled by the well-known Kohlrausch-Williams-Watts function with a shape exponent β larger than one. This parameter is furthermore found to be independent of both waiting time and wave-vector, leading to the possibility to rescale all the correlation functions to a single master curve. The dynamics in the glassy state is additionally characterized by different aging regimes which persist in the deep glassy state. These features seem to be universal in metallic glasses and suggest a nondiffusive nature of the dynamics. This universality is supported by the possibility of describing the fast increase of the structural relaxation time with waiting time using a unique model function, independently of the microscopic details of the system.

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Section: Discussionmentioning

confidence: 90%

“…The intensity autocorrelation function is related 31 and its determination allows capturing snapshots of the dynamics at different waiting times. The Siegert relation requires the temporal average to be equal to the ensemble average.…”

Section: Resultsmentioning

confidence: 99%

Compressed correlation functions and fast aging dynamics in metallic glasses

Ruta

Baldi²,

Monaco

et al. 2013

The Journal of Chemical Physics

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“…where /...S p is the ensemble average over the detector pixels mapping onto a single Q value and /...S is the temporal average over t 0 , was calculated by using a standard multiple t algorithm 45 .…”

Section: Discussionmentioning

confidence: 99%

Glass–glass transition during aging of a colloidal clay

et al. 2014

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Colloidal suspensions are characterized by a variety of microscopic interactions, which generate unconventional phase diagrams encompassing fluid, gel and glassy states and offer the possibility to study new phase and/or state transitions. Among these, glass-glass transitions are rare to be found, especially at ambient conditions. Here, through a combination of dilution experiments, X-ray photon correlation spectroscopy, small angle X-ray scattering, rheological measurements and Monte Carlo simulations, we provide evidence of a spontaneous glass-glass transition in a colloidal clay. Two different glassy states are distinguished with evolving waiting time: a first one, dominated by long-range screened Coulombic repulsion (Wigner glass) and a second one, stabilized by orientational attractions (Disconnected House of Cards glass), occurring after a much longer time. These findings may have implications for heterogeneously charged systems out-of-equilibrium and for applications where a fine control of the local order and/or long term stability of the amorphous materials are required.

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“…XPCS allows one to probe the dynamics of fluctuations on short length scales ( 100 nm) and long time scales (!10 À4 s) (Malik et al, 1998;Madsen et al, 2010). Information about the dynamics is obtained by studying the time correlation of the intensity scattered by a system in a dynamic regime when illuminated with coherent light.…”

Section: Introductionmentioning

confidence: 99%

On the use of two-time correlation functions for X-ray photon correlation spectroscopy data analysis

Bikondoa

2017

J Appl Crystallogr

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Multi-time correlation functions are especially well suited to study nonequilibrium processes. In particular, two-time correlation functions are widely used in X-ray photon correlation experiments on systems out of equilibrium. One-time correlations are often extracted from two-time correlation functions at different sample ages. However, this way of analysing two-time correlation functions is not unique. Here, two methods to analyse two-time correlation functions are scrutinized, and three illustrative examples are used to discuss the implications for the evaluation of the correlation times and functional shape of the correlations.

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Beyond simple exponential correlation functions and equilibrium dynamics in x-ray photon correlation spectroscopy

Cited by 179 publications

References 73 publications

Compressed correlation functions and fast aging dynamics in metallic glasses

Compressed correlation functions and fast aging dynamics in metallic glasses

Glass–glass transition during aging of a colloidal clay

On the use of two-time correlation functions for X-ray photon correlation spectroscopy data analysis

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