Syntheses and Charaterization of Gd₂Zr_2-xCe_xO₇(0.0≤x≤2.0)

In order to get the physical properties, phase change and microstructure of waste forms containing plutonium, cerium with four valences was used as the simulacrum for plutonium with tetravalence. Pyrochlore Gd₂Zr₂O₇ as waste forms was prepared by Gd₂O₃, ZrO₂ and CeO₂ powders with high temperature solid-state method. The solid solubility of pyrochlore Gd₂Zr₂O₇ is ranged from 0 to 100% (in mole) dosage. Waste forms were characterized with density, rigidity, phase composition and micromorphology. The results show that density and rigidity H_V increase with x, rigidity and the addition of Ce satisfy the relation: H_V＝661.272 73+223.936 36x(R²＝0.946 38). When x＝0.0, the waste forms are single pyrochlore structure; when x＝0.2, the waste forms transform from pyrochlore into fluorite structure. In the interval 0.2≤x≤2.0, the waste forms are single fluorite structure. Microstructure of waste forms is not regular and plate-like.