Effects of Metal Doping on Thermoelectric Properties of Arc-Melted and Hot-Pressed β-Rhombohedral Boron

Abstract

Thermoelectric properties of metal (V, Co, Zr, Sr, W)-doped β-rhombohedral boron (β-Boron) were examined in the temperature range from 353 K to 1073 K. Doping with V (V_1.5B₁₀₅), which preferentially occupy the A₁ sites, results in a great increase of electrical conductivity σ and a negative Seebeck coefficient S, while doping Co, Zr, Sr or W (M_1.0B₁₀₅, M=Co, Zr, Sr or W) also increases the σ though S remains positive. By crushing and hot pressing as-melted samples, the thermal conductivity κ was decreased to almost half of that of arc-melted samples. As a result, V-doped and hot-pressed n-type β-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.