Zr doped β-rhombohedral boron: widely variable Seebeck coefficient and structural properties

Abstract

The doping effect of zirconium on the structure, Seebeck coefficient and electrical resistivity of β-rhombohedral B was studied for the metal rich concentration range ZrxB100-x, 1.88x2.75. Structural studies proved the Zr atoms mainly in E and D voids for the metal rich compositions, and also elucidated the minor Zr occupancies of the N, F and A1 holes. Seebeck coefficients were effectively shifted within a wide range of positive and negative values by varying the Zr content (p-type: Smax ~ +420 µVK-1 at 673 K for x=1.88; n-type: Smax ~ -670 VK-1 at 473 K for x=2.74). Electrical resistivities generally followed the Mott’s relation for the variable-range hopping. Excellent compositional agreement has been observed between structural and thermoelectric properties discontinuities.