Chemical durability of Gd2Zr2O7 transparent ceramics under different pH conditions

Abstract

In this study, the chemical durability of Gd2Zr2O7 transparent ceramics was investigated under different pH environments. The influence of acidic and alkaline environments on the leaching behavior of Gd2Zr2O7 immobilization matrix were studied to simulate the disposal of nuclear waste forms in deep geological landfills. The measured results demonstrate that the normalized leaching rates in acidic environments are higher than those in alkaline and neutral environments. The macroscopic color of all samples fades after leaching, and the visible range in-line transmittance of the leached transparent ceramics decreases slightly at pH ≤ 9. The leaching behavior leads decrement of lattice volume and increment of surface roughness, but it exhibits no significant effect on the surface elemental distribution. Never the less, Gd2Zr2O7 transparent ceramic exhibits excellent chemical durability in weak alkaline environment, and the leaching process leads to the discoloration of Gd2Zr2O7 transparency.