Thermal transport properties of uranium dioxide by molecular dynamics simulations

Anisotropic thermal conductivity in uranium dioxide

“…MD simulations applying the direct method 6,7 were used to calculate UO 2 thermal conductivity. All calculations were performed with the scalable parallel short-range MD code 32 and closely follow the study by Watanabe et al 8 A constant heat flow was imposed in a rectangular cuboid simulation cell by allowing thermal energy to transmit from a hot plate to a cold plate separated by half of the simulation cell length. The thickness of the hot and cold plates was 5.463 Å, that is, one UO 2 unit cell.…”

“…These MD results inspired a detailed experimental study of the UO 2 thermal conductivity as a function of temperature with a thermal gradient applied in different crystallographic directions on oriented single crystal bars. We find that the overall shape of the of the simulation cell for the temperature gradient applied in the o1004 and o1114 lattice directions at 300 K. The lines represent linear and quadratic fits to the data used for extrapolation to infinite length (k N ) of the simulation cells 7,8 . The inset compares the experimentally measured thermal conductivity values (Exp.)…”

“…Our consideration of anisotropic UO 2 thermal conductivity originated from molecular dynamics (MD) simulations using the direct method [6][7][8] , which calculates thermal conductivity by measuring the temperature gradient in a rectangular cuboid with heat added and removed at a hot and cold plate, respectively. The simulations predict large differences for the effective thermal conductivity in the o1004 o1104 and o1114 crystallographic directions at 300 K, see Fig.…”

“…1a. In an attempt to eliminate boundary condition artifacts related to scattering by the hot and cold plates, the thermal conductivity is obtained for infinite simulation cell length by extrapolation 7,8 . Figure 1a shows…”

Elastic and thermal properties of hexagonal perovskites

“…The thermal expansion depends linearly on the frequency dependent Grüneisen parameter, while the thermal conductivity depends on the square of the Grüneisen parameter. 21,22 To more clearly identify the effects of crystallography, we determined the thermal conductivity of HoGaO 3 in both the orthorhombic and hexagonal structures; although the orthorhombic structure has the lower energy, the hexagonal structure is metastable allowing the determination of its thermal transport properties. As Fig.…”