Thermoelectric properties of metal-doped β-rhombohedral boron

For the development of n-type high-temperature thermoelectric materials in boron-rich solids, β-rhombohedral boron was doped with V, Cr, Fe or Zr, and the relationship between the electrical properties below the room temperature and the site occupancies were investigated. The electrical conductivity increases with an increase in the occupancies of the A₁ sites by metal atoms. The Seebeck coefficients of metal-doped β-boron decrease with increasing metal concentration except for Zr-doped β-boron. Both the electrical conductivity and the Seebeck coefficient increase with temperature, reflecting the variable-range hopping conduction. The power factor increases with temperature, and the n-type β-boron whose power factor is three orders of magnitude larger than that of pure β-boron at the room temperature was obtained by V- or Cr-doping at higher metal concentration