P-type Bi$_{1-x}$Sb$_{x}$ above 300K

Heavily-doped p-type bismuth was theoretically predicted to be a good thermoelectric material. Tin is a known monovalent acceptor in the semimetal bismuth, but even at moderate Sn concentrations, the material becomes compensated and even switches n-type as temperature increases. Antimony, on the other hand, is always p-type; this work aims at finding the concentration in Bi$_{1-x}$Sb$_{x}$ alloys where acceptor behavior on Sn switches. Historically, the regime where Bi$_{1-x}$Sb$_{x}$ exhibits p-type conduction has been limited to cryogenic temperatures, with Seebeck coefficients switching negative below 300K Tin-doped single crystals of composition Bi$_{1-x}$Sb$_{x }$with 0.16$<$x$<$0.5 have been synthesized using the Bridgeman method followed by a lengthy anneal. We measure and report here thermopower, electrical resistivity, thermal conductivity and thus zT measured from 2-400K and 2K carrier density as calculated from the Shubnikov-de Haas effect.