Effects of metal doping on thermoelectric properties of arc-melted and hot-pressed β-rhombohedral boron

Thermoelectric properties of metal (V, Co, Zr, Sr, W)-doped beta-rhombohedral boron (beta-Boron) were examined in the temperature range from 353 K to 1073 K. Doping with V (V1.5B105), which preferentially occupy the A, sites, results in a great increase of electrical conductivity a and a negative Seebeck coefficient S, while doping Co, Zr, Sr or W (M1.0B105, M = Co, Zr, Sr or W) also increases the sigma though S remains positive. By crushing and hot pressing as-melted samples, the thermal conductivity K was decreased to almost half of that of arc-melted samples. As a result, V-doped and hot-pressed n-type beta-Boron had a ZT value of about 0.01 at 885 K, which approaches that of boron carbide, which exhibits the maximum ZT value among the boron-rich icosahedral cluster solids.