Grain Boundary Energy Interpolation for Uranium Dioxide

Abstract

Grain boundary (GB) energies have an effect on the frequency with which certain GBs are present in a material. Since GBs have a direct impact on a material's properties, knowledge of GB energies is useful in determining those properties. This knowledge is difficult to establish due to an incomplete understanding of the atomic structure of a GB. Previous research has successfully created an interpolation function for the GB energies of face-centered cubic (fcc) metals. An extension of this work was recently done by creating an interpolation function for uranium dioxide (UO 2 ), which has a fluorite crystal structure. This work improves the accuracy of that function. Molecular dynamics (MD) simulations were used to calculate more accurate GB energies for UO 2 , and new fitting parameters were calculated from those results. Comparison with previous work shows an overall improvement. * For cubic crystals, rotations of 90°, 180°, or 120°about any 〈100〉, 〈110〉, or 〈111〉 axis respectively is a symmetry operation. Thus, the 〈100〉 set is four-fold symmetric (360°/90°= 4), the 〈110〉 set is two-fold symmetric (360°/180°= 2), and the 〈111〉 set is three-fold symmetric (360°/120°= 3).