Rapid synthesis and chemical durability of Gd2Zr2-xCexO7 via SPS for nuclear waste forms

To investigate the rapid immobilization of tetravalent actinides (An(4+)), Ce4+ was used as simulated nuclear waste to be incorporated in Gd2Zr2O7 ceramic. A series of compositions with the general formula of Gd2Zr2-xCexO7 (0.0 <= x <= 2.0) were rapidly fabricated through SPS process. That the Gd2Zr2-xCexO7 (0.0 <= x <= 1.0) ceramics with a single phase can be obtained at 1600 degrees C within 3 min as x was below 1.5. The lattice parameter and volume increase with enhancement of Ce content. The samples are in cubic-shaping crystal structure, as well as orderly arranged atomic layers. Meanwhile, the bulky density of samples increase with elevated Ce content, which is much higher than the conventionally obtained ones. In addition, the normalized release rates of Gd, Zr and Ce elements in Gd2ZrCeO7 waste form are kept in low values (lower than 10(-4) g.m(-2) d(-1)), which exhibits a reliable chemical stability.