Effective medium theory of binary thermoelectrics
  The transport coefficients of disordered media are analyzed using direct numerical simulation and effective medium theory. The results indicate a range of materials parameters for which disorder leads to an enhanced power factor. This increase in power factor is generally not accompanied by an increase in the figure of merit $ZT$, however. It is also found that the effective electrical conductivity and electronic contribution to the thermal conductivity are not generally proportional to each other in the presence of disorder. 
Paul M. Haney
cond-mat.mtrl-sci