The effect of weberite arrangement on the mechanical, thermophysical, and electronic properties of actinide-doped Gd2Zr2O7

Abstract

This study employs density functional theory with Hubbard U correction (DFT+U) to investigate the influence of the weberite motif on the elastic moduli, Debye temperature, thermal conductivity, and electronic structures of actinides (Th, U, Np, Pu, and Am) in disordered Gd₂Zr₂O₇. The key distinction between the disordered and ordered Gd₂Zr₂O₇ phases lies in the presence of the weberite motif. The incorporation of actinides into Gd₂Zr₂O₇ containing the weberite motif results in a slight reduction in the elastic moduli and thermal conductivity, compared to actinides incorporated into Gd₂Zr₂O₇ without the weberite motif. This suggests that the actinide-doped disordered Gd₂Zr₂O₇ retains its thermophysical stability. Additionally, the inclusion of actinides into the Gd₂Zr₂O₇ phase with weberite motifs significantly lowers the Debye temperature relative to actinide incorporation in Gd₂Zr₂O₇ without the motif. This observation indicates a higher thermal expansion coefficient for actinide doping in disordered Gd₂Zr₂O₇, which may be more favorable for the application of pyrochlores in extreme environments. These findings highlight the critical role of the weberite motif in influencing the mechanical and thermophysical properties of actinide-doped disordered pyrochlores.