Ideal Strengths and Bonding Properties of UO₂ under Tension

By performing density functional theory plus U calculations, we systematically study the structural, electronic, and magnetic properties of UO₂ under uniaxial tensile strain. The results show that the ideal tensile strengths along the 100, 110, and 111 directions are 93.6, 27.7, and 16.4 GPa at strains of 0.44, 0.24, and 0.16, respectively. After electronic-structure investigation for tensile stain along the 001 direction, we find that the strong mixed ionic/covalent character of U–O bond is weakened by the tensile strain and there will occur an insulator to metal transition at strain over 0.30.