Planar Zintl-phase high-temperature thermoelectric materials XCuSb(X=Ca,Sr,Ba)with low lattice thermal conductivity

A recent discovery of high-performance Mg_(3)Sb_(2) has ignited tremendous research activities in searching for novel Zintl-phase compounds as promising thermoelectric materials.Herein,a series of planar Zintl-phase XCuSb(X=Ca,Sr,Ba)thermoelectric materials are developed by vacuum induction melting.All these compounds exhibit high carrier mobilities and intrinsic low lattice thermal conductivities(below 1 W·m^(−1)·K^(−1) at 1010 K),resulting in peak p-type zT values of 0.14,0.30,and 0.48 for CaCuSb,SrCuSb,and BaCuSb,respectively.By using BaCuSb as a prototypical example,the origins of low lattice thermal conductivity are attributed to the strong interlayer vibrational anharmonicity of Cu–Sb honeycomb sublattice.Moreover,the first-principles calculations reveal that n-type BaCuSb can achieve superior thermoelectric performance with the peak zT beyond 1.1 because of larger conducting band degeneracy.This work sheds light on the high-temperature thermoelectric potential of planar Zintl compounds,thereby stimulating intense interest in the investigation of this unexplored material family for higher zT values.