Generation of electric-field stabilized zirconium monoxide secondary phase within cubic zirconia

Flash sintering of cubic yttria-stabilized zirconia has been studied via in situ energy dispersive diffraction. A secondary rocksalt-phase zirconium monoxide was observed emerging from the primary fluorite-phase zirconium dioxide, previously only observed as a thin interlayer at metal-oxide interfaces, upon application of a direct current electric field. The average secondary phase intensity rose over extended flow of direct current through the ceramic, faded upon removal of the field and disappeared entirely upon application of an alternating current electric field. The results indicate that the sustained application of a direct current electric field can result in significant electrochemical reduction of zirconia under high current density conditions. Poor sinterability and cracking under direct current is apparent and potential mechanisms discussed therein. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

Flash sintering of cubic yttria-stabilized zirconia was studied using in situ energy dispersive diffraction. It was found that a secondary rocksalt-phase zirconium monoxide emerged from the primary fluorite-phase zirconium dioxide under a direct current electric field, but disappeared entirely under an alternating current electric field. The results suggest that direct current can lead to electrochemical reduction of zirconia, impacting sinterability and potential mechanisms are discussed.