Electronic Structures and Thermoelectric Properties of Sb-Doped Type-VIII Clathrate Ba₈Ga₁₆Sn₃₀

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The type-VIII clathrate Ba₈Ga₁₆Sn₃₀ shows a high figure of merit (ZT) in the middle temperature range 470–670 K. ZT enhancement through Sb doping has recently been reported in p-type Ba₈Ga₁₆Sn₃₀. In this study, calculations to determine the electronic structures and thermoelectric properties of Sb-doped Ba₈Ga₁₆Sn₃₀ are performed using the WIEN2k code. The energy derivative of density of states [∂ρ(ε)/∂ε]_ε=EF for valence band is lower in the Sb-doped Ba₈Ga₁₆Sn₃₀ than in non-Sb-doped one, though the density of states [ρ(ε)]_ε=EF of both system are almost the same as that for Ba₈Ga₁₆Sn₃₀. Except for the signs, the calculated Seebeck coefficients for the p- and n-type Sb-doped and non-Sb-doped Ba₈Ga₁₆Sn₃₀ are similar.