Fig. 2: Equilibrium electrical state of a flat grain boundary.
From: Electrochemical drag effect on grain boundary motion in ionic ceramics
The charge density (a) and electrostatic potential (b) distribution in the vicinity of the grain boundary for 2 at% Fe-doped SrTiO3, for selected misorientations in gray: Δθ = 10° (darkest), Δθ = 20°, and Δθ = 30° (lightest). The grain boundary core is positively charged as a result of excess \([{\,\text{V}}_{\text{O}\,}^{\cdot \cdot }]\) being chemically attracted to the interface, surrounded by a negative space charge layer. The increase in the positive core charge with misorientation increases the interfacial electrostatic potential, which, in turn, extends the electrostatic potential gradients in front of the grain boundary.
