Ab initio density functional theory study of uranium solubility in Gd2Zr2O7 pyrochlore

TL;DR

This study uses ab initio density functional theory to analyze uranium solubility in Gd2Zr2O7 pyrochlore, revealing preferred substitution sites and structural stability at low uranium levels, aligning with experimental data.

Contribution

It provides a detailed theoretical analysis of uranium substitution sites in Gd2Zr2O7 pyrochlore, highlighting site preferences and structural effects not previously characterized.

Findings

Uranium prefers substituting for B-site gadolinium atoms.

Gd2Zr2O7 maintains structure at low uranium levels.

Lattice constants vary linearly with uranium content.

Abstract

In this study, an ab initio calculation is performed to investigate the uranium solubility in different sites of Gd2Zr2O7 pyrochlore. The Gd2Zr2O7 maintains its pyrochlore structure at low uranium dopant levels, and the lattice constants of Gd2(Zr2-yUy)O7 and (Gd2-yUy)Zr2O7 are generally expressed as being linearly related to the uranium content y. Uranium is found to be a preferable substitute for the B-site gadolinium atoms in cation-disordered Gd2Zr2O7 (where gadolinium and zirconium atoms are swapped) over the A-site gadolinium atoms in ordered Gd2Zr2O7 due to the lower total energy of (Gd2-yZry)(Zr2-yUy)O7. The theoretical findings present a reasonable explanation of recent experiment results.