The onset mechanism of flash sintering dense 8YSZ

In this work, the onset mechanism of flash sintering (FS) of fully dense 8 mol% yttria-stabilized zirconia (8YSZ) was investigated. The conductivity behavior during the incubation stage was measured, which indicated that oxygen vacancy diffusion induced nonlinear conductivity in addition to Joule heating. When the blackening front was close to the anode, a flash event was triggered. The asymmetric temperature distribution along the sample was recorded during the full process; the highest temperature was located between the center point and the anode, and the cathode had the lowest temperature. We believe that the percolation mechanism with the contributions of oxygen vacancies and internal reactions dominated the onset process.