Synthesis, crystal structure and thermoelectric properties of β-K 2Bi 8Se 13 solid solutions

Abstract

Solid solution series of the type K 2Bi 8-xSb xSe 13, K 2-xRb xBi 8Se 13 as well as K 2B 18Se 13-xS x were prepared and the distribution of the atoms (Bi/Sb, K/Rb and Se/S) on different crystallographic sites, the band gaps and their thermoelectric properties were studied. The distribution Se/S appears to be more uniform than the distribution of the Sb and Rb atoms in the β-K 2B 18Se 13 structure that shows preference in specific sites in the lattice. Band gap is mainly affected by Sb and S substitution. Seebeck coefficient measurements showed n-type character for all Se/S members. In the Bi/Sb series an enhancement of p-type character was observed. The thermoelectric performance as well as preliminary high temperature measurements suggest the potential of these materials for high temperature applications.