Electronic structure and thermoelectric properties of skutterudites

Thermoelectric properties on Yb filled skutterudite antimonides are calculated by using a realistic band structure are discussed from the point of view of electronic structure. The electronic structure is calculated by the full-potential linearized augmented plane-wave (FLAPW) method with the local density approximation (LDA). In the band structure calculation of YbFe4Sb12 4f electron is treated by two ways: one is as itinerant electron, another is as localized electorn in the Yb ion. In the itinerant case Yb ion shows mixed valence between divalent and trivalent, in the localized case trivalent. In both cases the band structure near Fermi level is characterized by Fe: 3d orbital. The band structure of YbCo4Sb12 is calculated as Yb-filling CoSb3, which is a n-type material, The f orbital of the Yb ion is strongly hybridized with the valence band, the conduction band near the bottom affects 6s and 5d of Yb atomic orbital. Electronic transport coefficients axe calculated within relaxation time approximation using the linearized Boltzmann equation. Then the electron velocity is calculated by the Fourier interpolation method, The calculated coefficient of thermoelectric power alpha/T is 0.07muV/K-2 at room temperatures, which is about 1/2 of the experimental value.