Technique to control specimen electric current during a flash state with alternating current electric fields

Abstract

A simple technique to control the specimen electric current during flash sintering was developed using AC electric fields in 3 mol% Y₂O₃-doped ZrO₂. Flash sintering is characterized by the occurrence of a flash event, i.e., a spike in the specimen electric current, which makes it difficult to control the specimen electric current at/after the flash event for AC electric fields. However, AC electric fields are very attractive from the viewpoint of a suppression of the severe reduction arising from the unidirectional ionic flow during the flash event, which is a fatal phenomenon with DC electric fields. In this study, we develop a simple technique to control the AC electric fields at/after the flash event by limiting the AC electric fields under certain values. As a result, the flash state after the flash event is successfully maintained. Further, it is found that 3 mol% Y₂O₃-doped ZrO₂ compacts prepared by DC- and AC-flash sintering emit blue fluorescence (FL) under 254 nm ultraviolet light. The blue FL is not obtained in the compacts prepared by conventionally-sintering. The application of electric fields is confirmed to result in the blue florescent properties of 3 mol% Y₂O₃-doped ZrO₂ compacts.