The electronic and lattice components of the thermal conductivity of polycrystalline Bi88Sb12

An analysis is made of the thermal conductivity data from polycrystalline samples of Bi₈₈Sb₁₂. The specimens include the undoped alloy and material incorporating either Se or Sn as a doping agent. The thermal conductivity measurements were made between 100 K and 300 K in magnetic fields of up to 1 tesla. Data for the electrical conductivity, Seebeck coefficient and Hall coefficient were also available. Attempts were made to determine the electronic component of the thermal conductivity (including the bipolar contribution) by two different techniques. In the first of these, the Lorenz number was calculated using the parameters that had been obtained from the transport coefficients other than the thermal conductivity. In the second method, the variation of the electrical and thermal conductivities with magnetic field was used. The first method was clearly unsatisfactory since, in some cases, it led to a negative lattice component of the thermal conductivity. The second approach was superior in that it gave reasonably consistent values for the lattice conductivity but it leaves us with the still unresolved problem of an electronic component that is considerably smaller than expected. Possible reasons for the anomaly are discussed