Rapid preparation of Gd2Zr2−xCexO7 waste forms by flash sintering and their chemical durability.

A simple and low-energy-consuming approach for preparing ceramic nuclear waste forms is greatly preferred for disposal of ever-increasing amounts of radioactive nuclear wastes. Herein, simulated radionuclide Ce could be rapidly incorporated into Gd 2 Zr 2 O 7 ceramic via flash sintering technique. Under an electric field of 250 V/cm, Gd 2 Zr 2−x Ce x O 7 (0.0 ≤x ≤ 1.2) waste forms with a single phase of defect-fluorite were flash sintered at relatively low temperatures of 889–997 °C in 60 s. The onset temperature of flash sintering was decreased with the enhancement of Ce content. Furthermore, the density and grain size of Gd 2 Zr 2−x Ce x O 7 waste forms were increased with the increase of the current limit. The nearly full dense Gd 2 Zr 2−x Ce x O 7 waste forms were flash sintered at a current limit of 200 mA. The normalized leaching rates of Gd, Ce, and Zr in Gd 2 Zr 0.8 Ce 1.2 O 7 after 28 d were 6.5475 × 10−5, 1.1624 × 10−7, and 1.1613 × 10−7 g·m−2·d−1, respectively, which exhibited a good chemical durability. • Gd 2 Zr 2−x Ce x O 7 waste forms are rapidly prepared by flash sintering. • Rapid solid reaction and densification occurs simultaneously in flash sintering. • Oxygen vacancies are formed in the flash sintering of Gd 2 Zr 2 O 7 and CeO 2. • Current limit has a significant effect on grain size and densification. • Gd 2 Zr 2−x Ce x O 7 waste forms exhibit good chemical durability. [ABSTRACT FROM AUTHOR]