| The thermoelectric properties of polycrystalline BiSb alloys have been measured at temperatures from 80 K to 300 K. Prior theory suggested that the lattice thermal conductivity of these alloys would decrease with grain size for grain sizes less than about 5 microns. The samples made in the present work, with grain sizes ranging from 1.1 to 19 microns, were produced by hot consolidation of powders. The lattice thermal conductivity is found to decrease as the grain size is reduced in reasonable agreement with model predictions. However, it is possible that the effect may be due to the scattering of phonons on point or line defects that may be present as a consequence of powder metallurgy. The electrical conductivity was also found to decrease with grain size, but to a greater degree than the lattice thermal conductivity so that the net result on the thermoelectric figure of merit was not favorable. |
