Incorporation of lanthanides into zirconia: a study of solid phase transformations

Zirconia (ZrO2) is the primary corrosion product of the Zircaloy cladding material surrounding nuclear fuel rods [1]. It has also been envisioned as a ceramic host phase for specific high- level waste streams, immobilizing radionuclides and being able to become a protective barrier. In the case of doped ZrO2 matrices, a very high radiation tolerance has been reported, however, discrepancies exist regarding the role of the different structural polymorphs in the high radiation resistance. Ce has been used as a surrogate for Pu due to comparable chemical properties in the oxidation states +III and +IV, similar ionic radius, and its easier handling [2]. In the current study, phase transformations occurring in the ZrO2 material when doped with Ce(IV) and Gd(III), have been explored.