We now consider the lattice (phonon) contribution to the thermal conductivity, κ latt . As for the electrical properties, we focus mainly on the average (scalar) values representative of films or pressed pellets, which we denote κ latt . The calculated κ latt of the three oxychalcogenides is shown in Fig. (a), and Table compares values at T = 800 K to similar calculations on the bismuth chalcogenides Bi 2 Ch 3 , SnS and SnSe, and the oxide perovskite SrTiO 3 . Table : Comparison of the averaged lattice thermal conductivity κ latt of the three oxychalcogenides examined in this work at T = 800 K to the bismuth chalcogenides Bi 2 S 3 , Bi 2 Se 3 and Bi 2 Te 3 , SnS and SnSe, and SrTiO 3 . We also show the decomposition of the κ latt into harmonic and lifetime components κ/τ CRTA and τ CRTA as defined in Eq. 4. 0.34 0.44 0.77 Bi 2 Se 3 (P nma) 0.18 0.20 0.91 Bi 2 Se 3 (R 3m) 0.68 0.30 2.28 Bi 2 Te 3 (R 3m) 0.33 0.20 1.64 SnS (P nma) 0.80 0.75 1.07 SnSe (P nma) 0.59 0.38 1.56 SrTiO 3 (I4/mcm) 1.74 10.6 0.17