First-Principles Study of Thermo-Physical Properties of Pu-Containing Gd(2)Zr(2)O(7)

A density functional theory plus Hubbard U method is used to investigate how the incorporation of Pu waste into Gd(2)Zr(2)O(7) pyrochlore influences its thermo-physical properties. It is found that immobilization of Pu at Gd-site of Gd(2)Zr(2)O(7) has minor effects on the mechanical and thermal properties, whereas substitution of Pu for Zr-site results in remarkable influences on the structural parameters, elastic moduli, elastic isotropy, Debye temperature and electronic structure. The discrepancy in thermo-physical properties between Gd(2−y)Pu(y)Zr(2)O(7) and Gd(2)Zr(2−y)Pu(y)O(7) may be a result of their different structural and electronic structures. This study provides a direct insight into the thermo-physical properties of Pu-containing Gd(2)Zr(2)O(7), which will be important for further investigation of nuclear waste immobilization by pyrochlores.