Electrical transport properties of Co-based skutterudites filled with Ag and Au

TL;DR

This study uses theoretical calculations to analyze the electrical transport properties of Co-based skutterudites filled with Ag and Au, identifying promising compositions for thermoelectric applications.

Contribution

It provides the first detailed theoretical analysis of Ag and Au filled Co-based skutterudites, highlighting their potential for enhanced thermoelectric performance.

Findings

Au filling improves thermoelectric properties in CoSb3.

Ag filling in CoP3 suggests potential for low thermal conductivity.

Certain Au-filled compounds show promising Seebeck coefficients and conductivities.

Abstract

This work presents theoretical calculations of the electrical transport properties of the Ag, Au, and La fractionally filled bulk skutterudites: CoSb3, CoAs3, and CoP3. Density functional theory (DFT), along with projector augmented wave (PAW) potentials, was used to calculate bulk band structures and partial density of states. The Seebeck coefficient (S), electrical conductivity (s), and power factor (S2 s) were calculated as a function of temperature and filling fraction using the momentum matrix method along the entire first Brillouin zone. Calculated trends in the electrical transport properties agree with previously published experimental measurements for p-type unfilled and La filled CoSb3. The calculated S and s values for the Ag and Au filled compounds indicates that the most promising electronic properties are exhibited by p-type Au0.125(CoSb3)4, Au0.25(CoSb3)4, and Au(CoSb3)4. Au is therefore recommended as a promising filler for improved thermoelectric properties in cobalt antimonides. Ag is also a good filler for cobalt phosphides; the creation of a negative indirect band gap is observed in Ag(CoP3)4, which indicates semimetallic behavior, so this compound may possibly exhibit lower thermal conductivity than metallic CoP3. Finally, we recommend future directions for improving the thermoelectric figure of merit of these materials.