Effect of Electric Current on Trijunction Equilibrium and Grain Rotation of Lossy Dielectrics

To understand the structural stability of lossy dielectrics under the action of an electric current, the effect of an electric current on the stress evolution, the change of chemical potential, and the electric energy stored in a grain boundary is examined. Analytical forms of the stress, chemical potential, and electric energy are obtained, which depend on the current density. The concept of an apparent grain boundary energy, which is a linear function of the square of the current density, is introduced. One needs to use the apparent grain boundary energy in analyzing the equilibrium state of a trijunction. An expression for the rate of grain rotation is proposed, which includes the contributions of the change of chemical potential and the electric energy in grain boundaries.