Effects of electric field on the entropy, viscosity, relaxation time, and glass-formation
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By using the known formalism for the effect of an externally applied electric field, E, on thermodynamics of a dielectric material, we calculated the field-induced configurational entropy factor, ΔSconf (E)/E(2), of 50 dipolar liquids, including those whose static permittivity, εs, decreases on cooling. The field induced change, ΔSconf (E), is found to be experimentally detectable only when E is on the order of 10(5) V∕cm, a value less than the dielectric breakdown field strength of some liquids but in the range of nonlinear dielectric response. We argue that the dielectric response is formally nonlinear already for E > 0, and then show that the difference between the Langevin-function and the extrapolated linear response is < 0.15% for E in the 10(5) V∕cm range. Therefore, such high E values may be used to estimate ΔSconf (E). We conclude that (i) for E in the 10(5) V∕cm range, ΔSconf (E) is high enough to produce a measurable change in the viscosity and relaxation time of some ultraviscous liquids with prominent dipolar interactions, thereby changing their glass formation temperature, and (ii) application of E would reversibly transform, isothermally, some liquids to glass, and transform some glasses to liquid. Finally, we suggest that the effect of E can be used to determine the merits of the models for non-Arrhenius kinetics.
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