Structural order-disorder transitions and phonon conductivity of partially filled skutterudites.

Filled skutterudites are high-performance thermoelectric materials and we show how their phonon conductivity is greatly influenced by the topology of the filler species. We predict (ab initio) the phase diagram of Ba(x)Co4Sb12 and find several stable configurations of Ba ordering over the intrinsic voids. The phonon conductivity predicted using molecular dynamics shows a minimum in the two-phase mixture regime, dominated by significantly reduced long-range acoustic phonon transport.