Preparation of Gd2Zr2O7 nanoceramics from two-step thermal treatment and the aqueous durability analysis.

Gd 2 Zr 2 O 7 ceramics demonstrate important prospect in the immobilization of high-level radioactive wastes (HLWs). In this study, Gd 2 Zr 2 O 7 nanoceramics were fabricated using two-step method, where Gd 2 Zr 2 O 7 nanopowder was firstly synthesized by solvothermal method and Gd 2 Zr 2 O 7 nanoceramics were subsequently sintered via self-propagating chemical furnace plus quick pressing (SCF/QP). The characterization results display that the Gd 2 Zr 2 O 7 nanocrystalline ceramics with average grain size of 78 nm and bulk density of 5.53 g cm−3 were successfully prepared. The results of MCC-1 static leaching experiments show that the normalized release rate (LR i) of Gd is 2.2 × 10−2 g m−2•d−1 on the first day and converges to 1.2 × 10−3 g m−2•d−1 after 42 days. Zr shows superior chemical stability as the 21 days LR Zr value is as low as 2.7 × 10−6 g m−2•d−1, which becomes constant as the leaching duration prolongs. [ABSTRACT FROM AUTHOR]