Conversely, however, the τ CRTA are shorter than comparable chalcogenides, which may be indicative of stronger anharmonicity. In our recent work on the titanate perovskites we found that the strong bonding led to large group velocities (large κ/τ CRTA ) but also to strong phonon-phonon interactions and hence short lifetimes (short τ CRTA ). The analysis here therefore suggests the the κ latt of the oxychalcogenides may be determined by a similar trade-off.