First-principles study of point defects in U₃Si₂: effects on the mechanical and electronic properties

Abstract

In recent years, the U3Si2 has been proposed to be alternative to uranium dioxide (UO2) as nuclear fuel material because of its intrinsically high uranium density and thermal conductivity. However,...

Understanding xenon and vacancy behavior in UO2, UN and U3Si2: a comparative DFT+Ustudy

“…Not considering spin-orbit coupling (SOC) for UO 2 can yield reasonable lattice parameters and bulk moduli, [99][100][101][102] and the SOC effect is not considered in most of investigations of U 3 Si 2 [103][104][105] due to its negligible impact on its structural, mechanical and electronic properties. 51 For the defective UN system, although the formation energies of point defects with and without the consideration of SOC exhibit a significant decrease, energetic value comparisons show the same trend. 71 However, using SOC for UN is crucial to simultaneously reproduce the experimental observed magnetic order, magnetic moment and unit cell volume, 106 whereas the SOC effect on the band structure, total density of state (DOS), formation energy and cohesive energy of UN is of little significance.…”

“…Moreover, the magnetism changes with the initial magnetic moment. 51 The non-magnetic (NM) structure of U 3 Si 2 has been confirmed to be an effective solution to predict formation energy, 43 which is also used in current work as a consequence. The NM structure of U 3 Si 2 requires a U eff value of 4 eV.…”

“…The production of a Xe-vacancy cluster is an endothermic process in both UO 2 and UN host crystals, 31,32 and thus, there is a finite solubility of Xe in their matrices. In contrast to UO 2 25,27,[33][34][35][36][37][38] and UN, 31,[39][40][41] very few studies 21,[42][43][44][45][46][47][48][49][50][51][52] have focused on the thermodynamic behavior of point defects and impurity Xe in U 3 Si 2 .…”

The effects of point defects on thermal-mechanical properties of BiCuOTe: a first-principles study

“…Under Voigt–Reuss–Hill (VRH) approximation, the bulk modulus ( B ), Young's modulus ( E ) and shear modulus ( G ) can be deduced from the elastic constants: 39 …”

“…Meanwhile, C 44 is found to be larger than C 66 , implying that the shear deformation along the (100) plane is more difficult than that along the (001) plane. 38,39 As shown in Table 4, the introduction of vacancy defects has less effect on the ability to resist uniaxial deformation than that to resist shear deformation, in view of C 11 and C 33 obviously larger than the other elastic constants, except for O vac . It is also noted that the introduction of O vac and Te vac defects makes the shear deformation along the (001) plane more difficult than that along the (100) plane.…”