Hexabromobenzene-Doped Bismuth Chalcogenide Solid Solutions Prepared through Melt Solidification in a Liquid

Abstract

n-Type Bi₂Te₃–Bi₂Se₃ solid solutions containing 6, 8, and 10 mol % Bi₂Se₃ and doped with hexabromobenzene (C₆Br₆) and excess tellurium have been prepared by extruding granules produced by melt solidification in a liquid. The solid solutions have been characterized by X-ray microanalysis and microstructural analysis using a scanning electron and an optical microscope, and their mechanical and thermoelectric properties have been studied. Their ultimate strength, fracture strain, and elastic coefficient have been evaluated from room-temperature compression test results. The electrical conductivity, Seebeck coefficient, and thermal conductivity of the solid solutions have been measured in the temperature range 100–700 K. The temperature behavior of the Seebeck coefficient and electrical conductivity in the temperature range 150–300 K has been shown to differ from that predicted theoretically. The highest thermoelectric figure of merit of the solid solutions, (ZT)_max, is ~0.9 at temperatures from 320 to 390 K.