Fig. 2: Joule heating distribution of a ceramic green body during flash sintering.
Inset (a) shows a section of the 3YSZ microstructure as shown in region (II) in Supplementary Fig. 1. Inset (b) illustrates the spatial distribution of the Joule heating being generated at Tf = 1000K. Charge flows through the particle contacts and surfaces (see streamlines). Inset (c) shows the Joule heating at Tf = 1200K. As the sample temperature increases, charge flow is suppressed across those particles that develop wider depletion zones, while locally finding surficial and small angle grain boundaries that favor charge transport. Inset (d) shows that at Tf = 1300K, \([{{\rm{V}}}_{{\rm{O}}}^{\cdot \cdot }]\) greatly increases at the grain boundary cores, which promotes charge to flow in a larger number of percolating paths. The increase in charge transport paths further increase the local Joule heating and results in the onset of flash.
