Regensburg 2022 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 24: Non-equilibrium Phenomena in Materials Induced by Electrical and Magnetic Fields 4

MM 24.7: Topical Talk

Wednesday, September 7, 2022, 18:00–18:30, H45

Electric fields effects in ionic conductors during flash sintering and ion exchange — •Mattia Biesuz, Gian Domenico Soraru, and Vincenzo Maria Sglavo — University of Trento, Trento, Italy

Electric fields can drive ceramic ionic conductors out of the equilibrium dictated by temperature, composition, and pressure. These phenomena can be used to promote ceramics sintering or ion exchange.

Herein, we explore flash sintering in oxygen ionic conductors (YSZ and GDC) evidencing the presence of some electrochemical effects producing alterations of the defect chemistry and activating n-type electronic conductivity. This enhances the conductivity of the green sample, increases the electric power dissipation and contributes to the activation of the flash leading to sudden densification of ceramics. The pivotal role of electrochemical reduction during DC-flash sintering impacts the thermal history of the flashed samples generating strong thermal gradients between the cathode and anode which can be enhanced or removed by changing the quality and type of the used electrodes. The electrochemical description of flash sintering in oxygen ion conductors well explains the electrode configuration and atmosphere effects on the flash processes.

Electrochemical phenomena are, however, pivotal also in other ionic conductor systems subjected to flash-like processes. It is shown that the electrode material choice strongly affects the flash behavior and modifies the glass composition in the vicinity of electrodes. Hence, electric fields can be to modify the surface glass or ceramics composition improving mechanical and functional properties.