Ab initio lattice thermal conductivity of bulk and thin-film $α$-Al$\mathrm{_2}$O$\mathrm{_3}$
The thermal conductivities ($κ$) of bulk and thin-film $α$-Al$_2$O$_3$ are calculated from first principles using both the local density approximation (LDA), and the generalized gradient approximation (GGA) to exchange and correlation. The room temperature single crystal LDA value $\sim39~$W/m$~$K agrees well with the experimental values $\sim35-39~$W/m$~$K, whereas the GGA values are much smaller $\sim$26$~$W/m$~$K. Throughout the temperature range, LDA is found to slightly overestimate $κ$ whereas GGA strongly underestimates it. We calculate the $κ$ of crystalline $α$-Al$\mathrm{_2}$O$\mathrm{_3}$ thin films and observe a maximum of 79$\%$ reduction for $10~$nm thickness.
cond-mat.mtrl-sci↗