ANISOTROPIC ELECTRICAL PROPERTIES OF EXTRUDED Bi_85Sb_15 DOPED WITH Pb AND Te

摘要

Anisotropy in the electrical conductivity, thermoelectric power ,and Hall coefficient of extruded Bi_85Sb_15 doped with Pb and Te was studied in magnetic fields up to 74×10~4 A/m at temperatures from 77 to 300 K. The observed anisotropy was shown to be due to the preferential alignment of the material caused by extrusion. The heat treatment, dopant type ,and doping level have a strong effect on anisotropy. The results are interpreted in terms of crystal structure and defect chemistry.