The impact of a magnetic ion on the thermoelectric properties of copper-rich quaternary selenides

Abstract A series of copper-based p -type chalcogenide semiconductors, Cu 2+ x B Ge 1− Se 4 ( = Zn, Fe; 0 ⩽ 0.15), was prepared by high-temperature methods, to explore the impact replacement closed-shell ion, Zn , with magnetically active, Fe cation. Powder x-ray diffraction in conjunction Rietveld refinement reveals that zinc-containing materials are described kesterite-type structure (space group: I 4 ˉ ) and contain trace amounts secondary phases, whereas iron analogues, stannite-type I $\bar 42m$?> 2 m ), single-phase behaviour persists 0.1. Excess copper ions lead formation holes electrical resistivity both is reduced from stoichiometric end members. In case iron-containing materials, this shown be due an increase hole mobility, µ . This decrease offsets observed reduction Seebeck coefficient exhibit improvement thermoelectric performance. The lower leads higher figures-of-merit, compared those at same level excess. maximum figure-of-merit, ZT 0.3 attained for 2.075 FeGe 0.925 comparatively low temperature 575 K. ca 62% member phase ca. 67% than zinc analogue substitution.