The calculated thermal-conductivity curves for the five filled models (Fig. ) show that filling produces a modest reduction in 𝜅 latt compared to pristine CoSb3, with a somewhat intricate trend among the five fillers. A comparison of values at 300 and 600 K (Table , Table .3) show that the 𝜅 latt fall in the order of Ar ≈ He > Ne ≈ Kr > Xe, with reductions of 8-9, 11-12 and 15 % compared to CoSb3. This correlates with the 𝑓 ̃X: He and Ar have the highest 𝑓 ̃X and produce the smallest reduction in 𝜅 latt , Ne and Kr have similar 𝑓 ̃X and produce similar reductions, and Xe has the lowest 𝑓 ̃X and has the largest effect on 𝜅 latt . It is therefore evident that the effect of the fillers on the 𝜅 latt depends both on their mass and how strongly they interact with the framework.