Electronic Band-Structure Calculations of Ba8Me x Si46-x Clathrates with Me = Mg, Pd, Ni, Au, Ag, Cu, Zn, Al, Sn

Abstract

Clathrate materials of AlSi, CuSi or NiSi type consisting of abundant elements have a realistic chance of becoming useful thermoelectrics in the near future, because the rattling effect due to their crystal cage structure provides a large figure of merit ZT even in experiments measured under large temperature gradients. In the search for better thermoelectrics, new element combinations in the clathrate type I structure with cubic space group Pm3n were calculated using VASP ab initio software. Predictions of the Seebeck coefficient were made by checking the electronic band structure and density of states for a large variety of input data. For x values around 4 to 6 in the structural formula Ba8MexSi46−x the substituents Cu, Au, and Ag are best for good thermoelectric behavior, which is discussed in this paper as a result of the low electron–phonon interaction parameter.