Reduction of lattice thermal conductivity from planar faults in the layered Zintl compound SrZnSb2

The layered Zintl compound SrZnSb2 is investigated using transmission electron microscopy (TEM) to understand the low lattice thermal conductivity. The material displays out-of-phase boundaries with a spacing from 100 down to 2 nm. Density functional theory calculations confirm that the TEM-derived defect structure is energetically reasonable. The impact of these defects on phonon scattering is analyzed within the Debye-Callaway model, which reveals a significant reduction in the acoustic phonon mean free path. This enhancement in phonon scattering leads to an similar to 30% reduction in lattice thermal conductivity at 300 K. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3549821]