Fast Fabrication of High‐Performance CoSb3‐Based Thermoelectric Skutterudites via One‐Step Yb‐Promoted Peritectic Solidification

Abstract As a most promising mid‐temperature thermoelectric material, CoSb 3 ‐based bulk material exhibits an applicable figure‐of‐merit ( ZT ) of more than one. However, their fabrication is historically time‐consuming due to the long‐time solid‐state phase transitions from CoSb 2 to CoSb 3 . To overcome this challenge, here, a fast one‐step process is developed to fabricate n‐type Yb‐doped CoSb 3 with stable ZT of 1.12 at 765 K in <5 h. Experiments confirm Yb promotes peritectic reactions of CoSb + Liquid → CoSb 2 and CoSb 2 + Liquid → CoSb 3 , optimizes power factor, and suppresses thermal conductivity. Moreover, the dense grains, induced by the one‐step crystallization, result in outstanding mechanical properties with a Young's modulus of 171.4 GPa and a hardness of 8.8 GPa in the Yb‐doped CoSb 3 . This study indicates that the fast one‐step fabrication route can effectively promote the practical applications of CoSb 3 ‐based thermoelectrics and provide guidance for thermoelectric fabrication via rational phase design.