New Nanofibrous Structured CsAg 5 Te 3 Exhibiting Ultralow Thermal Conductivity and High Figure of Merit.

Low-thermal-conductivity materials are ideal candidates for high-performance thermoelectric materials. CsAg 5 Te 3 is a new metal-rich chalcogenide with an inherent low-thermal conductivity. However, due to its complex crystal structure, obtaining high-purity CsAg 5 Te 3 poses a serious challenge. In addition, the high price of pure metals Cs, Ag, and Te leads to the high cost of traditional solid-state methods for preparing CsAg 5 Te 3 . To address these issues, the preparation of CsAg 5 Te 3 with a nanostructured fiber morphology was carried out using a low-energy-intensity scalable microwave method. The CsAg 5 Te 3 nanofibers were then assembled using spark plasma sintering technology to prepare CsAg 5 Te 3 bulk with a layered structure. The lattice thermal conductivity of the CsAg 5 Te 3 nanostructured material is 0.19 W m -1 K -1 , which is almost the lowest among the state-of-the-art thermoelectric materials. Finally, at 673 K, the maximum zT value of CsAg 5 Te 3 can reach ∼0.67. This study provides a feasible pathway for low-cost preparation of nanostructured thermoelectric materials.