Interaction between gadolinium zirconate and LiCl–Li2O melt

The interaction between Gd₂Zr₂O₇ and molten LiCl–Li₂O (2 wt%) was studied for 24–52 h at 650–710 °C in an argon atmosphere. Gd₂Zr₂O₇ is analyzed as a promising structural material for sensors used during pyrochemical reprocessing of spent nuclear fuel and for long-term storage or final disposal of high-level nuclear wastes.The chemical stability of Gd₂Zr₂O₇ relative to the components of the LiCl–Li₂O melt was thermodynamically evaluated. The surface morphology and structure of the samples before and after the experiment were analyzed using an X-ray diffractometer and scanning electron microscopy. The formation of a new Li⁺-doped phase based on Gd₂Zr₂O₇ and the Gd₂O₃ evolution onto the material surface was revealed by the X-ray diffraction analysis (XRD). Changes in the microstructure of the samples confirm the presence of large particles in the surface layer corresponding to the Gd₂O₃ phase, which is in good agreement with the XRD data. A profilometer was used to measure the roughness of the ceramics. Presumably, the thickness of the lithium-doped Gd₂Zr₂O₇ film, which is inhomogeneously distributed over the surface of the samples, was 3 μm. Therefore, it was found that dense Gd₂Zr₂O₇ (F) and Gd₂Zr₂O₇ (P) ceramics can be used in LiCl–Li₂O (2 wt %) as a structural material resistant to the high-temperature chemical attack.