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, CoSb₃‐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 CoSb₂ to CoSb₃. To overcome this challenge, here, a fast one‐step process is developed to fabricate n‐type Yb‐doped CoSb₃ with stable ZT of 1.12 at 765 K in <5 h. Experiments confirm Yb promotes peritectic reactions of CoSb + Liquid → CoSb₂ and CoSb₂ + Liquid → CoSb₃, 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 CoSb₃. This study indicates that the fast one‐step fabrication route can effectively promote the practical applications of CoSb₃‐based thermoelectrics and provide guidance for thermoelectric fabrication via rational phase design.