In-flash immersion-and-quench of yttria-stabilized zirconia into liquid nitrogen yields an electronic conductor

It is known that once flash has been triggered with furnace heating, specimens can be held in the state of constant flash, or Stage III, outside the furnace at ambient temperature. The flash is maintained by the current flowing through the specimen. We show that this in-flash state is further preserved when the specimen is immersed into liquid nitrogen. Furthermore, we show that the nature of the material existing in Stage III can be quenched by turning off the power to the specimen while it is still in immersion. Normally, during furnace cool, the specimens revert to their original state when the flash is turned off. However, yttria-stabilized zirconia retrieved from in-flash immersion-and-quench is discovered to be electronically conductive at room temperature, at approximately 11 S/m. The conductivity declines somewhat when the specimen is heated slightly above room temperature, suggesting metal-like behavior. These in-flash immersed specimens, with their Stage III structure frozen in place, will enable ex-situ characterization of changes in the crystallographic, chemical, defect and electronic structure induced by flash activation.