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 Gd2Zr2O7 ceramic via flash sintering technique. Under an electric field of 250 V/cm, Gd2Zr2-xCexO7 (0.0 <= x <= 1.2) waste forms with a single phase of defect-fluorite were flash sintered at relatively low temperatures of 889-997 degrees 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 Gd2Zr2-xCexO7 waste forms were increased with the increase of the current limit. The nearly full dense Gd2Zr2-xCexO7 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)Cc(1.2)O(7) after 28 d were 6.5475 x 10(-5), 1.1624 x 10 (-7), and 1.1613 x 10(-7) g center dot m(-2)center dot d(-1), respectively, which exhibited a good chemical durability.