Improved thermoelectric figure of merit of self‐doped Ag_8–xGeTe₆ compounds with glass‐like thermal conductivity

Abstract Nonstoichiometric Ag_8–xGeTe₆ (x = 0, 0.01, 0.02, 0.04) compounds with complex crystal structure are demonstrated to exhibit very low thermal conductivities of <0.28 W/m K, comparable with the calculated theoretical minimum thermal conductivity κ_min. Ag deficiency leads to the improved electrical properties and a maximum thermoelectric figure of merit ZT of 0.85 has been obtained at 623 K for Ag_7.99GeTe₆, about 30% increase compared to that of stoichiometric Ag₈GeTe₆. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)