On the exceptional negative Seebeck effect in 3d-doped β-rhombohedral boron

Abstract

Interstitial doping with 3d-elements impact the electronic properties of β-rhombohedral boron significantly; in some cases high negative Seebeck coefficients occur. The explanation by simple charge transfer is excluded. We attribute these effects to the correlation among the diluted 3d atoms generating a specific system of electronic states in the band gap. The interaction with Ogitsu’s antiferromagnetic Ising model, describing the incomplete occupancy of regular B sites, is probable. Details depend on the kind of dopants, occupied sites, and occupancies. Very low V, Cr, and Ni contents evoke extraordinary high negative Seebeck coefficients at ambient conditions; e.g. VB 190: S = 450 μVK −1 at 270 K, a shift of more than 1000 μVK −1 compared with pure boron. Structural and electronic properties of B:V, B:Fe, B:Cu and some other 3d transition metal solid solutions in β-rhombohedral boron are discussed.