Transport properties of tetrahedral, network-forming ionic melts

Agarwal, Manish ; Ganguly, Abir ; Chakravarty, Charusita (2009) Transport properties of tetrahedral, network-forming ionic melts Journal of Physical Chemistry B, 113 (46). pp. 15284-15292. ISSN 1520-6106

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Official URL: http://pubs.acs.org/doi/abs/10.1021/jp903694b

Related URL: http://dx.doi.org/10.1021/jp903694b

Abstract

Molecular dynamics simulations of liquid silica and beryllium fluoride are performed using the van Beest-Kramer-van Santen and transferable rigid ion model potentials, respectively, in order to compare transport properties. The ionic conductivity (σ ), shear viscosity (η ) and ionic self-diffusivities (D±) are computed over a fairly wide range of temperatures and densities and deviations from Arrhenius behavior along different isochores is studied. The Stokes-Einstein relation is shown to hold over the entire range of state points, though the effective hydrodynamic radius shows small variations due to thermal fluctuations, compression, and local tetrahedral order. Several alternative tests of the Nernst-Einstein relation are implemented which show that significant network-formation in the anomalous regime leads to a breakdown of this relationship. The relaxation times, τσ and τM, associated with the decay of the charge-flux and pressure ACFs respectively, are computed. In the anomalous regime, as the tetrahedral network formation progresses, τM increases rapidly while τσ shows very little variation, indicating a decoupling of charge and momentum transport processes.

Item Type:Article
Source:Copyright of this article belongs to American Chemical Society.
ID Code:75970
Deposited On:28 Dec 2011 13:05
Last Modified:28 Dec 2011 13:05

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