Thermodynamic model of electric-field-induced pattern formation in binary dielectric fluids

Abstract

An electric-field-induced phase transition and pattern formation in a binary dielectric fluid layer are studied using a coarse-grained free energy functional. The electrostatic part of the free energy is a nonlinear functional of the dielectric function, which depends in turn on the local colloidal concentration. We determine the phase co-existence curve and find that beyond a critical electric field the system phase separates. Accompanying the phase separation are patterns similar to those observed in a spinodal decomposition of an ordinary binary fluid. The temporal evolution of the phase separating patterns are discussed both analytically and numerically by integrating a Cahn-Hilliard type of equation.

An electric-field induced dynamical state in dispersions of charged colloidal rods

“…Spatial variations in the dielectric constant can give rise to electric eld induced instabilities. 5,6,9,10 For the present experiments, however, the eld strengths (up to about 5 V mm À1 ) are too low to induce sufficient dielectric. Furthermore, the concentration of fd-virus particles is very low (the volume fraction is about 0.002), which most probably leads to a minor effect due to dielectric polarization even for much higher eld strengths.…”

“…The function I describes the frequency dependence of single particle torques, while the function h characterizes the interaction strength between polarization charges. The dimensionless frequency U is defined in eqn (6).…”

“…Spinodal-like phase separation can be induced in ferro-uids by such a strong DC electric eld (larger than 750 V mm À1 ), 5 which can be theoretically described on the basis of a thermodynamic approach that includes the eld-induced dielectric contributions to the free energy. 6 There is a large body of literature on further electric-eld induced instabilities in other types of so-matter systems, mostly in two-dimensional connement like in thin polymer lms, which is beyond the scope of the present study.…”

Lithium‐Battery Anode Gains Additional Functionality for Neuromorphic Computing through Metal–Insulator Phase Separation

“…In the case of the Cahn‐Hilliard (or Van der Waals) approximation, , where g h ( c ) is the homogeneous free energy density and κ is the gradient penalty. This model has recently been used to describe phase separation in binary fluids, solids, and polymers driven by applied electric fields. In the case of LTO, an expression for the chemical part of the free energy has already been developed and parameterized in a recent phase‐field model for Li‐ion battery simulations, also including electrochemical intercalation reactions and polaron diffusion, but neglecting large electric fields within the active material, which become important in the new application to neuromorphic computing.…”

Dielectric Breakdown by Electric-field Induced Phase Separation

“…In many dielectric mixtures that phase separate under electric fields, e.g. colloids, [29][30][31][32] polymers, 33 amorphous solids, 23 electrolytes, 27 the electric permittivity depends on the corresponding species concentration. 34 The effect of this dependence can be understood in the simple case of a binary mixture, where the applied electric field contributes to the total chemical potential μ, i.e.…”