The role of an electrode in the formation of new phase nuclei in dielectrics

Abstract

Contrary to some theoretical considerations, we show that electric field favours the formation of both vapour bubble in superheated liquid and liquid drop in supersaturated gas. In the latter case the field must exceed some threshold value. The work required for nucleus formation decreases significantly near the electrode. The conclusions are based on the expression for this work that we use in our analysis in the presence of electric field, and are in agreement with experimental observations.

Thermodynamics of Crystal Nucleation in an External Electric Field

“…The observed increase in the nucleation rate is in agreement with the theoretical prediction, since the value of K a -K c for ZTC is far above zero. Also, this result is in conformity with the report of V. S. Vorob'ev et al [40]. Onset time of nucleation (hours) (I r ) minimum 0 -10 5 5.3 0.55 0.5 x 10 6 5.125 0.45 0.75 x 10 6 5.05 0.41 The increase of I r at the later stage is caused by the decrease of scattering centers in the solution due to the sedimentation of the nucleated crystals.…”

Critical Parameters of Gas Cavities in Dielectric Liquids Stressed with High Electric Fields

“…* corresponding author; e-mail: igor.timoshkin@eee.strath.ac.uk However, the application of the external electric field to the liquid changes this situation. As has been shown in [3,4], the external electric field promotes the formation of the bubbles through the change in the thermodynamical properties of the liquid and its phase equilibrium conditions. The electrostrictional tensile stress exerted on the liquid in the external field results in the "rupture" of the liquid and the formation of gas cavities.…”

“…Hence, the electrode's tip is the most probable area in the liquid where a bubble can be formed. The work A c (E) required to form the bubble with the critical size R c (E), may be written as [3,4,6,7]:…”

“…where E t and E n are the normal and tangential components of the field at the bubble/liquid interface [4]. The electric field on the electrode tip can be modelled at one extreme by the field generated by an ideal charged point.…”

“…These two limiting cases require different values of the parameter x in Eq. (1), which have been obtained in [3,4,6,7] and are used here for analysis of the electric field on the electrode's tip.…”