(Mg, Co, Ni, Cu, Zn)1−xLixO is a type of high-entropy oxide that has high ionic conductivity at room temperature and is used as a solid electrolyte. (Mg, Co, Ni, Cu, Zn)1−xLixO was successfully synthesized from precursor powder by applying reactive flash sintering for less than 4 min at room temperature (25 °C). AC and DC electric fields were independently applied to sinter ceramic samples; consequently, AC and DC electric field application resulted in relative densities that exceeded 90% and 80%, respectively. X-ray diffraction spectra of samples revealed the existence of a clear halite structure with an insignificant impurity phase, proving that (Mg, Co, Ni, Cu, Zn)1−xLixO crystals were successfully produced.

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Oxygen vacancy plays an important role in the flash sintering (FS) process. In defect engineering, the methods to create oxygen vacancy defect include doping, heating, and etching, and all of them often have complex process or equipment. In this study we used dielectric barrier discharge (DBD) as a new defect engineering technology to increase oxygen vacancy concentration of green billet with different ceramics (ZnO, TiO2 and 3 mol% yttria-stabilized zirconia (3YSZ)). With a 10 kHz AC power supply, the low-temperature plasma was generated and the specimen could be treated in different atmosphere. The effect of DBD treatment was influenced by atmosphere, treatment time, and voltage amplitude of power supply. After DBD treatment, the oxygen vacancy defect concentration in the ZnO samples increased significantly, and the resistance test showed that the conductivity of the samples increased by 2-3 orders of magnitude. Moreover, the onset electric field of ZnO FS decreased from 5.17 kV/cm to 0.86 kV/cm at room temperature, while in the whole FS the max Power dissipation decrease from 563.17 W to 27.94 W. The defect concentration and conductivity of the green billets for TiO2 and 3YSZ also changed by DBD, and then the FS process was modified. It is a new technology to treat green billet of ceramic in very short time, applicable to other ceramics, and beneficial to regulate the FS process.

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