Ab Initio Investigation of Gadolinium Zirconate Pyrochlore for Substantial Nuclear Waste Applications

Study’s Excerpt/Novelty This study uses density functional theory (DFT) simulations to investigate the structural and electrical properties of gadolinium zirconate pyrochlore (Gd2Zr2O7), a compound considered for high-level nuclear waste immobilization. The research provides detailed insights into the lattice parameters, band structure, and density of states, revealing the conductive behavior of Gd2Zr2O7 and highlighting its resistance to amorphization. These findings enhance the understanding of Gd2Zr2O7's potential as a robust material for nuclear waste containment, offering a scientific basis for future ab initio investigations and practical applications in nuclear waste management. Full Abstract Nuclear energy is an alternative low CO2 emission strategy anticipated to mitigate future high energy demand. Radioactive wastes generated from spent nuclear fuel are the major challenge of utilizing nuclear reactors as a source of energy. Pyrochlore compounds are among the rigorous nuclear waste forms considered for High-level waste immobilization. Density functional theory (DFT) based on first-principles simulations was used to study gadolinium zirconate pyrochlore's structural and electronic characteristics (Gd2Zr2O7). The lattice parameters of optimized Gd2Zr2O7 are α = β = γ = 60.0 ° and a = b = c = 7.635A. The conduction band minimum and valence band maximum structure was discovered to be stable and approached the experimental lattice constant. The overlapping of the conduction and valence bands in Gd2Zr2O7 indicates its conductive behavior in terms of its electrical characteristics. Due to a usual underestimating of band gap energy in DFT based on electron exchange handling, the estimated band gap energy of 0.09 eV differed from experimental measurements. In addition to band gap energy computation, the computed total density of states and projected density of states show different orbital dominations and energy levels. The findings showed that the Gd2Zr2O7 ceramic compound had good resistance to amorphization and could be used for further ab initio investigations.