Thermoelectric properties and electronic structure of CoSb 3 doped with Se and Te

Abstract

This work presents structural and electron transport properties of Se- and Te-doped CoSb 3 skutterudites in relation to results of electronic structure calculations performed for this system. The physical quantities were determined from crystal structure studies and measurements of transport coefficients: electrical conductivity, thermal conductivity and Seebeck coefficient as a function of composition and temperature. The electronic structure of CoSb 3 was calculated using the Korringa–Kohn–Rostoker method with the LDA framework. Dispersion curves E( k) in CoSb 3 computed for experimental crystallographic parameters exhibit a very narrow indirect energy gap at the Fermi level, which however strongly varies along different k-directions. The KKR valence and conduction band curvatures reflect effective masses estimated from experimental data well. The effect of doping CoSb 3 with Se and with Te as well as the dopants’ influence on density of electronic states was investigated by the KKR method combined with the coherent potential approximation (CPA). This method was also used to show an impact of various crystal defects on electronic structure in pure Se- and Te-doped CoSb 3.