Flash in argon atmosphere yields electronically conducting yttria‐stabilized zirconia at ambient temperature

Abstract

This is the second report on the retention of electronic conductivity in yttriastabilized zirconia at room temperature after cooling down from the state of flash . In the first report, the specimens (which were flashed in air) were quenched by in-flash immersion into liquid nitrogen. Now we show that if the specimens are flashed in Ar in a glove box (O 2 < 1 ppm), then they remain electronic conductors under nominal cooling. Indeed, the conductivity of the Ar-flashed specimens is higher than the conductivity of LN 2 -quenched samples. In both instances, their conductivity increases with flash current. In contrast, specimens flashed in air, and then air-cooled, become insulating akin to their original condition. We propose a possible pathway for such a reaction. In addition, we report measurements of the interface resistance at the anode and the cathode by the four-point technique. In air, the resistance at anode is higher than at the cathode, and the sum of the interface resistances is about one half of the total end-to-end resistance.

Capacitive discharge in flash experiments: A discussion of the charged species

“…The in-operando interface resistance at the anode and the cathode, from both Ar and air experiments, measured by the four-point method, is reproduced in Figure S2. 10…”

“…In contrast, the specimens flashed in Ar remained electronically conducting. 10 Therefore, the discharge in SO2 occurs solely through the external resistor, while in Ar it occurs via the external resistor and the internal resistance of the specimen, effectively connected in parallel. Therefore, for the case of SAr, the total discharge resistance would have been lower than the external resistance.…”

Comment on “Flash in argon atmosphere yields electronically conducting yttria‐stabilized zirconia at ambient temperature” by Jo et al., J Am Ceram Soc. 2023;106:5133–5139

“…In a recent publication in this journal, Jo et al 1 state: "In a recent paper, 2 Bechteler et al showed that the optical spectra from a graphite furnace heated to 1200 • C also show electroluminescent spectra." We wish to point out that this statement is factually incorrect and that as a consequence, Jo et al seriously misinterpret the scientific implications of our results.…”

“…The error in the above quotation 1 is that the sample referred to is a freestanding piece of graphite heated to 1200 • C in an alumina tube furnace with external heating elements, as is clearly described in Ref. [2].…”

“…Following the above quotation from Ref. [1], Jo et al go on to state that we have "failed to recognize a recent publication showing the flash phenomenon in carbon fibers 4 with electroluminescent spectra resembling those from flash experiments in ceramics." We are not convinced that the spectra in question show significant electroluminescence as claimed.…”