LAUSR

The development of new routes for the production of thermoelectric materials with low-cost and high-performance characteristics has been one of the long-term strategies for saving and harvesting thermal energy. Herein, we report a new approach for improving thermoelectric properties by employing the intrinsically low thermal conductivity of a quasi-one-dimensional (quasi-1D) crystal structure and optimizing the power factor with aliovalent ion doping. As an example, we demonstrated that SbCrSe3, in which two parallel chains of CrSe6 octahedra are linked by antimony atoms, possesses a quasi-1D property that resulted in an ultra-low thermal conductivity of 0.56 W m−1 K−1 at 900 K. After maximizing the power factor by Pb doping, the peak ZT value of the optimized Pb-doped sample reached 0.46 at 900 K, which is an enhancement of 24 times that of the parent SbCrSe3 structure. The mechanisms that lead to low thermal conductivity derive from anharmonic phonons with the presence of the lone-pair electrons of Sb atoms and weak bonds between the CrSe6 double chains. These results shed new light on the design of new and high-performance thermoelectric materials. A material that is counter-intuitively both a good electrical conductor and thermal insulator has been made by a team in China and the USA. The ideal thermoelectric material would have a high electrical conductivity and a low thermal conductivity. But this is challenging as both properties are facilitated by electrons. Now, Guoyu Wang (Chinese Academy of Sciences), Tao Yang, Xiaoyuan Zhou (Chongqing University) and their colleagues present an idea for seeking and optimizing low-dimensional thermoelectric materials. They started with a material with an intrinsically low thermal conductivity due to its atomic structure — the atoms in SbCrSe3 form one-dimensional chains held together by weak bonds, which inhibits thermal conduction. They then boosted the material's electrical conductivity by adding lead atoms. This approach could be applied to other materials with a similar one-dimensional atomic structure. SbCrSe3, described as a quasi-1D structure with CrSe6 double chains, possesses an intrinsic low thermal conductivity due to the large anharmonicity and weak chemical bonds. By substituting Sb with Pb, a peak ZT= 0.46 at 900 K is obtained in Pb0.05Sb0.95CrSe3 sample. This is about 24 times larger value than measured on pristine SbCrSe3.