Screening of the possible boron-based n-type thermoelectric conversion materials on the basis of the calculated densities of states of metal borides and doped β-boron

In order to screen candidates for n-type boride-based thermoelectric materials, the energetics of solid solutions of metallic atoms (Zr, Cr, and V) in beta -rhombohedral boron (beta -boron) and the densities of states of metal-borides of the CrB-, FeB-, MoB-. AlB2-, ReB2-, CaB6-, and UB12- types of structures and some tetraborides (YB4, CrB4, WB4, and MgB4) have been calculated using a first principle pseudopotential method within the local (spin) density approximation. It was properly concluded that Zr occupies the E site of beta -boron while V and Cr occupy the A(1) site. As for metal-monoborides and diborides, the 'rigid band approach' seems to be valid. The large negative Seebeck coefficient of FexCo1-xB is hopeful if Mott's explanation for the trend of the Seebeck coefficient for transition metal elements is valid for these borides. Y- or La- doped Ca(Sr, and Ba)B-6. can also be expected to be useful. (C) 2001 Elsevier Science Ltd, All rights reserved.