Preparation and electrical transport properties of VIII-type Sn-based single-crystal clathrates (Eu/Ba)8Ga16Sn30

In this work, the type-VIII Sn-based single-crystal clathrates with different stoichiometric ratios were prepared, and the structure of the samples was investigated. The results indicate that Eu atoms tend to replace Ba atoms. The introduced Eu atoms lead to a decrease in the materials’ melting point and the concentration of carriers, whilst the carrier mobility is increased. Despite the above, there was no obvious change on the electrical conductivity, and the lattice constant of samples were decreased. The Seebeck coefficient of the samples was found to be negative and its absolute value decreased with increasing Eu. The ZT values were found to be almost 0.46 at 550 k when the Eu initial ratio was equal to 0.25.