Chemical stability of Ce-doped zircon ceramics: Influence of pH, temperature and their coupling effects

Zircon was employed to immobilize simulated tetravalentactinide nuclide (Ce4+). Zr1-x,CexSiO4(0 <= x <= 0.10) ceramics were synthesized and their chemical durabilities were investigated systematically. The effects of pH and temperature on the chemical durability of the as-prepared compounds were investigated using the MCC-1 static leaching test, and their coupling effects were also explored. It was found that the normalized release rates of Ce in deionized water and alkaline solutions (pH=10) were smaller than those in acid solutions (p11=4). At a certain pH value, the normalized release rate of Ce (LRCe) increased with the temperature in the initial period. However, the leaching progress almost reached a balance after 14 days, and both of the pH and the temperature had slight impact on the leaching of Ce element. Moreover, the LR(Ce)were below 10(-5) g/m(2)/d after 42 days, which was lower than those of other nuclear waste forms in all discussed leachates.