The Thermal Conductivity of Nonmetallic Crystals

Manipulating the temperature dependence of the thermal conductivity of graphene phononic crystal

“…It is found that both κG and κGPnCs decrease with the temperature increasing as ~ T -α due to the Umklapp phonon-phonon scattering. Graphene has a T -1 behavior followed Slack relation, [51] which is consistent with previous work. increasing (shown in Fig.…”

“…It is known that the Slack relation is valid only when the long-range acoustic phonons dominate the thermal transport, meanwhile, both short-range acoustic and optical phonons are not important. [51,52] Sometimes, this precondition is not satisfied for structures with low thermal conductivity, such as zeolites [53] and GPnCs in our work.…”

Accident tolerant composite nuclear fuels

“…We calculate lattice governed thermal conductivity using QHA as implemented in QE code and two methods as discussed above: Slack model [5] and BTE code [8].…”

“…However, the thermal conductivity of thoria and ceria, are almost the same, while the average mass of atom in thoria is significantly higher (88 u versus 57 u). Slack also noted the correlation between the lattice thermal conductivity value and the Debye temperature [5]. We used here generalised Slack model, where we include contribution to the thermal conductivity from both acoustic and optical phonons and all inputs to the model are calculated as described previously [4,10] and above.…”

“…In this work, we evaluate the thermal conductivity of ceramic composites where the heat carriers are primarily phonons. In our previous work [4] we have found that the phonon contribution to the thermal conductivity of thoria, (an alternative fuel with a high melting point) can be well reproduced up to very high temperatures by a simplified Slack model [5] with the input parameters calculated using first principles molecular dynamics. Silicon Carbide (SiC) and Beryllium Oxide (BeO) are materials proposed to be used in accident tolerant fuel.…”