Thermophysical properties of Th_1−xU_xO₂pellets prepared by spark plasma sintering technique

Abstract

Th 17x U x O 2 solid solutions were synthesized by solid-state reaction and pelletized using the spark plasma sintering (SPS) technique. Pellets with 490% theoretical density were easily obtained within 40 min of sintering without any additive. The thermal conductivity, Young's modulus, Debye temperature, Vickers hardness, and heat capacity were systematically investigated, and the values for ThO 2 agree with the literature data. The thermal conductivity of Th 17x U x O 2 decreased with increasing U content up to x ¼*0.5. This tendency corresponds to phonon-point defect scattering theory. The Young's modulus and Debye temperature linearly decreased with increasing U content. The Debye temperature and standard molar entropy derived from the low-temperature heat capacity agree with the reported values.

Sintering trials of analogues of americium oxides for radioisotope power systems

“…One of the few mechanical properties reported for actinide oxides and their surrogates is Vickers hardness [7,29,30]. This standard technique can be conducted on small samples of material [31], and the data obtained allow an initial comparison with collated values of similar materials.…”

Improving empirical interatomic potentials for predicting thermophysical properties by using an irreducible derivatives approach: The case of thorium dioxide

“…For example, the optical phonon frequencies at the Γ point are predicted accurately via the PW, with this accuracy having been promised by the good agreement of the secondorder derivatives at the Γ point, as achieved during fitting. For thermal conductivity, the average experimental data of Xiao et al [50], Muta et al [65], and Bakker et al [66] at 300 K was 15.8 W/mK. And with respect to 15.8 W/mK, the percentage errors of the predicted thermal conductivity at 300 K are 12%, 43%, and 5% for SCAN, the CRG, and the PW, respectively.…”

“…Importantly, these properties were not used in the fitting and thus aid in ascertaining the predictive capabilities of the PW. Table V lists the calculated elastic constants, comparing with experiments from Clausen et al [62], Macedo et al [63], and Khanolkar et al [43,64]; Figure 1 presents the calculated phonon spectra, as compared with experiments from Bryan et al [44]; Figure 2 gives the calculated thermal conductivity, as compared with experiments from Xiao et al [50], Muta et al [65], and Bakker et al [66].…”

“…FIG.2. Calculated phonon thermal conductivity using SCAN, the CRG, and the PW at 50-600 K, compared with the experimental data from Xiao et al[50], Muta et al[65], and Bakker et al[66].…”

Thermal Energy Transport in Oxide Nuclear Fuel

“…The expansion of phonon scattering rates in Table 2 to SMRT requires recasting them into a form that accounts for differences between v p and v g . Using dispersion curves fit to inelastic neutron scattering data, 50 Deskins et al 555 implemented the SMRT approximation in the case of uranium substitutional defects in ThO 2 and compared the resulting temperature dependence of the thermal conductivity to measured values 604 and those from MD simulations 603 (Figure 29). This comparison shows that in these fluorite oxide systems, making the SMRT approximation still produces a reasonable description of the thermal conductivity in defect-bearing systems across a wide temperature range through the BTE.…”