The average and local structures of the (PbTe)1-x(PbS)x system of thermoelectric materials has been studied using the Rietveld and atomic pair distribution function (PDF) methods. Samples with 0:25 < x are macroscopically phase separated. Phase separation was suppressed in a quenched x = 0:5 sample which, nonetheless, exhibited a partial spinodal decomposition. The promising thermoelectric material with x = 0:16 showed intermediate behavior. Combining TEM and bulk scattering data suggests that the sample is a mixture of PbTe rich material and a partially spinodally decomposed phase similar to the quenched 50% sample. This results in a nano-meter scale inhomogeneous material that accounts for its very low thermal conductivity.
@article{arxiv.cond-mat/0612414,
title = {Phase separation and nanostructuring in the thermoelectric material PbTe1-xSx},
author = {H. Lin and E. S. Bozin and S. J. L. Billinge and J. Androulakis and C. H. Lin and M. G. Kanatzidis},
journal= {arXiv preprint arXiv:cond-mat/0612414},
year = {2007}
}