Defect modulation on CaZn1−xAg1−ySb (0 < x < 1; 0 < y <1) Zintl phases and enhanced thermoelectric properties with high zT plateaus

Abstract

Thermoelectric materials with high average figure of merit (zT) over the applied temperature range are crucial for power generation applications. In this report, a new Zintl series, CaZn_1−xAg_1−ySb (0 < x < 1; 0 < y < 1), was discovered and carefully investigated for their thermoelectric potential. These phases feature unique anionic layers with extensive Zn/Ag defects. Such a characteristic ensures very low intrinsic thermal conductivity and meanwhile considerably high electrical conductivity for the corresponding materials. For an optimized composition CaZn_0.4Ag_0.18Sb, decent thermoelectric performance was proved with a broad high zT plateau (zT ∼ 1.0) observed from 800 to 1100 K. The discovery of this new Zintl series not only provides us a valuable resource for exploring high zT materials, but also sheds some new light on the design of such thermoelectrics on the basis of defect modulation.