TY - JOUR
T1 - Design and fabrication of Gd2Zr2O7-based waste forms for U3O8 immobilization in high capacity
AU - Shu, Xiaoyan
AU - Lu, Xirui
AU - Fan, Long
AU - Yang, Ruizhu
AU - Ding, Yi
AU - Pan, Sheqi
AU - Zhou, Ping
AU - Wu, Yanlin
N1 - Funding Information:
The authors would like to thank financial supports from the National Natural Science Foundation of China (Nos. 41302028, 21507105), China Postdoctoral Science Foundation Funded Project (No. 2014M552384), Key Project of Sichuan Education Department (Nos. 14ZA0099, 15ZB0116), Foundation of Laboratory of National Defense Key Discipline for Nuclear Waste and Environmental Safety, Southwest University of Science and Technology (No. 15yyhk10), and the Doctor Foundation in Southwest University of Science and Technology (No. 14zx7168).
PY - 2016/6/1
Y1 - 2016/6/1
N2 - For the long-term radiotoxicity of uranium in nuclear waste, U3O8 were immobilized into Gd2Zr2O7 by ceramics solidification technology. Systematic samples (Gd1−4xU2x)2(Zr1−xUx)2O7 (0 ≤ x ≤ 0.25) were designed and prepared simultaneously via lattice substitution. The immobilization effects were identified by XRD, BSE, EDS, SEM, TEM, and XPS. The results show that 38.83 wt% U3O8 gets dissolved in Gd2Zr2O7 as a single phase (corresponding to 0 ≤ x ≤ 0.14 in (Gd1−4xU2x)2(Zr1−xUx)2O7), with U6+ occupies 56 at.% of the Gd3+ positions and U4+ occupies 14 at.% of the Zr4+ sites. The XRD patterns indicate that the solid solutions transform from pyrochlore to defective fluorite structure with enhanced uranium, and this is due to the difference in ionic radii between dopant ions (U6+ and U4+) and the host ions (Gd3+ and Zr4+). Grain coarsening and densification are observed with the increased uranium. Tetravalent and hexavalent uranium in waste forms are confirmed through XPS. This research reveals the good adaptability of Gd2Zr2O7 in immobilizing U3O8.
AB - For the long-term radiotoxicity of uranium in nuclear waste, U3O8 were immobilized into Gd2Zr2O7 by ceramics solidification technology. Systematic samples (Gd1−4xU2x)2(Zr1−xUx)2O7 (0 ≤ x ≤ 0.25) were designed and prepared simultaneously via lattice substitution. The immobilization effects were identified by XRD, BSE, EDS, SEM, TEM, and XPS. The results show that 38.83 wt% U3O8 gets dissolved in Gd2Zr2O7 as a single phase (corresponding to 0 ≤ x ≤ 0.14 in (Gd1−4xU2x)2(Zr1−xUx)2O7), with U6+ occupies 56 at.% of the Gd3+ positions and U4+ occupies 14 at.% of the Zr4+ sites. The XRD patterns indicate that the solid solutions transform from pyrochlore to defective fluorite structure with enhanced uranium, and this is due to the difference in ionic radii between dopant ions (U6+ and U4+) and the host ions (Gd3+ and Zr4+). Grain coarsening and densification are observed with the increased uranium. Tetravalent and hexavalent uranium in waste forms are confirmed through XPS. This research reveals the good adaptability of Gd2Zr2O7 in immobilizing U3O8.
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U2 - 10.1007/s10853-016-9831-9
DO - 10.1007/s10853-016-9831-9
M3 - Article
AN - SCOPUS:84961208776
VL - 51
SP - 5281
EP - 5289
JO - Journal of Materials Science
JF - Journal of Materials Science
SN - 0022-2461
IS - 11
ER -