Dramatic slowing of compositional relaxations in the approach to the glass transition for a bimodal colloidal suspension
SDW Hannam and PJ Daivis and G Bryant, PHYSICAL REVIEW E, 96, 022609 (2017).
Molecular dynamics simulation was used to study a model colloidal suspension with two species of slightly different sized colloidal particles in an explicit solvent. In this work we calculated the four interdiffusion coefficients for the ternary system, which were then used to calculate the decay coefficients D-+/- of the two independent diffusive modes. We found that the slower D- decay mode, which is associated with the system's ability to undergo compositional changes, was responsible for the long-time decay in the intermediate scattering function. We also found that a decrease in D- to negligible values at a packing fraction of phi(g) = 0.592 resulted in an extreme slow-down in the long-time decay of the intermediate scattering function often associated with the glass transition. Above phi(g), the system formed a long-lived metastable state that did not relax to its equilibrium crystal state within the simulation time window. We concluded that the inhibition of crystallization was caused by the inability of the quenched fluid to undergo the compositional changes needed for the formation of the equilibrium crystal.
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