Enhanced Thermoelectric and Mechanical Properties in Yb0.3Co4Sb12 with In Situ Formed CoSi Nanoprecipitates

Filled Skutterudites are one group of the most promising thermoelectric materials in real power generation applications. Herein, homogeneously dispersed multiscale CoSi nanostructures are successfully embedded into grains of the classic skutterudite system, Yb0.3Co4Sb12, by the in situ precipitation method. Such nanoprecipitates contribute much to the synergistic enhancement of thermoelectric and mechanical properties. On one hand, by the fine deployment of multiscale CoSi nanoparticles, the lattice thermal conductivity is significantly depressed almost to the theoretical limit because of the disrupted propagation of the heat-carrying phonons at phase boundaries. On the other hand, low-energy electrons are effectively screened due to the energy filtering effect by the interfacial potential barrier between the CoSi nanoprecipitate and the matrix, resulting in an enhanced power factor. Taken together, an enhanced peak ZT value of approximate to 1.5 at 873 K for the Yb0.3Co4Sb12/0.05CoSi composite is obtained with a high average ZT approximate to 0.95 between 300 and 873 K through decoupling the electrical and thermal transport parameters. Moreover, such a microstructure with multiscale CoSi nanoparticles shows significantly improved mechanical properties owing to particle hardening, making it more competitive for practical applications.