Electronic conductivity in gadolinium doped ceria under direct current as a trigger for flash sintering

• DOI: 10.1016/j.scriptamat.2020.01.007
• Publication Date: 2020-01-20T17:29:20Z
• Authors: Tarini Prasad Mishra; Rubens Roberto In...; Giorgio Speranza; Alberto Quaranta; Vincenzo M. Sglavo; Rishi Raj; Olivier Guillon; Martin Bram; Mattia Biesuz
• Keywords: info:eu-repo/classification/ddc/670; 670; 0205 materials engineering; 02 engineering and technology; 530; Defects; Electro-chemical blackening; Flash sintering; Gadolinium-doped ceria; Onset of the flash

Abstract In this paper, we discuss the progression of flash sintering in 10mol% gadolinium-doped ceria specimens. Flash transition is correlated with the generation of n-type electronic conductivity in air under direct-current bias. Its origin is attributed to partial reduction of the material which propagates from the cathodic-to-anodic region. The phenomenon was observed, in-situ, by monitoring the development of electrochemical blackening during the incubation period of the flash-experiment. Anomalous features, including shift in the valence band edge, shrinkage of the band-gap and change in the oxidation state of Ce in flashed samples was confirmed by X-ray photoelectron spectroscopy and diffuse reflectance measurements.