Study of cerium solubility in Gd2Zr2O7 by DFT + U calculations

The pyrochlore Gd2Zr2O7 has been proposed as a favorable structure for the immobilization of actinide nuclear waste, due to its high radiation resistance. Because CeO2 exhibits similar properties and radiation response to many actinide dioxides, it is often used as a surrogate for actinide dioxides in both experimental and computational studies. In the present work, we investigate the solubility of Ce in Gd2Zr2O7, as well as the energetic and electronic properties of Gd2−yCeyZr2O7, based on density functional theory plus Hubbard U correction (DFT + U). Our calculations show that Gd2Zr2O7 and Ce2Zr2O7 form a solid solution over the entire range of Ce content, in excellent agreement with experiments. The increased stability of the ordered pyrochlore structure with increasing Ce content may affect radiation resistance.

► Gd2Zr2O7 is an ideal candidate for the immobilization of actinide nuclear waste.
► Ce is used as a surrogate for U and Pu in both experimental and computational studies.
► We investigate the solubility of Ce in Gd2Zr2O7 based on DFT + U.
► Gd2Zr2O7 and Ce2Zr2O7 form a solid solution over the entire range of Ce content.
► The increased phase stability with increasing Ce content may affect radiation resistance.