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

Abstract

Gd2Zr2O7 ceramics demonstrate important prospect in the immobilization of high-level radioactive wastes (HLWs). In this study, Gd2Zr2O7 nanoceramics were fabricated using two-step method, where Gd2Zr2O7 nanopowder was firstly synthesized by solvothermal method and Gd2Zr2O7 nanoceramics were subsequently sintered via self-propagating chemical furnace plus quick pressing (SCF/QP). The characterization results display that the Gd2Zr2O7 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 (LRi) 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 LRZr value is as low as 2.7 × 10−6 g m−2•d−1, which becomes constant as the leaching duration prolongs.