Nanoscale α-structural domains in the phonon-glass thermoelectric material β-Zn₄Sb₃

A study of the local atomic structure of the promising thermoelectric material β-Zn₄Sb₃, using atomic pair distribution function (PDF) analysis of x-ray- and neutron-diffraction data, suggests that the material is nanostructured. The local structure of the β phase closely resembles that of the low-temperature α phase. The α structure contains ordered zinc interstitial atoms which are not long range ordered in the β phase. A rough estimate of the domain size from a visual inspection of the PDF is ≲10 nm. It is probable that the nanoscale domains found in this study play an important role in the exceptionally low thermal conductivity of β-Zn₄Sb₃.