Phase Formation Behavior and Thermoelectric Transport Properties of P-Type YbxFe3CoSb12 Prepared by Melt Spinning and Spark Plasma Sintering.

Kyu Hyoung Lee,Sang Hyun Bae,Soon-Mok Choi

doi:10.3390/ma13010087

Kyu Hyoung Lee, Sang Hyun Bae + Show 1 more

Open Access

https://doi.org/10.3390/ma13010087

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Abstract

Formation of multiple phases is considered an effective approach for enhancing the performance of thermoelectric materials since it can reduce the thermal conductivity and improve the power factor. Herein, we report the in-situ generation of a submicron-scale (~500 nm) heterograin structure in p-type Yb-filled (Fe,Co)4Sb12 skutterudites during the melt spinning process. Mixed grains of YbxFe3−yCo1+ySb12 and YbzFe3+yCo1−ySb12 were formed in melt spun ribbons due to uneven distribution of cations. By the formation of interfaces between two different grains, the power factor was enhanced due to the formation of an energy barrier for carrier transport, and simultaneously the lattice thermal conductivity was reduced due to the intensified boundary phonon scattering. A high thermoelectric figure of merit zT of 0.66 was obtained at 700 K.

Highlights

Skutterudite-based compounds such as n-type Co4 Sb12 -based and p-type (Fe,Co)4 Sb12 -based alloys are promising candidates for medium-high temperaturethermoelectric (TE) power generation applications [1,2,3]
We provide a rapid solidification process (RSP)-based synthesis route to prepare submicron-scale heterograin structure of p-type Yb-filled (Fe,Co)4 Sb12 skutterudites since RSP can trigger the generation of non-equilibrium or supersaturated phases due to high quenching speed
Phase formation behaviors of the melt spun ribbons and SPSed bulks were analyzed by the X-ray diffraction (XRD) method (EMPYRENA diffractometer, PANalytical B.V., The Netherlands) with Cu

Summary

Introduction

Skutterudite-based compounds such as n-type Co4 Sb12 -based and p-type (Fe,Co) Sb12 -based alloys are promising candidates for medium-high temperature (hot side temperature Thot ~ 500 ◦ C). Together with the filling approach, formation of multiple phases beyond the grain size reduction is commonly employed since this approach can reduce the κlat and/or improve the power factor (S2 σ) [8]. Introducing nanoparticles into the skutterudite matrix is one of the simplest routes to form materials with multiple phases, whereby a reduced κlat is obtained while maintaining the power factor of the skutterudite matrix [10,11]. We provide a rapid solidification process (RSP)-based synthesis route to prepare submicron-scale heterograin structure of p-type Yb-filled (Fe,Co) Sb12 skutterudites since RSP can trigger the generation of non-equilibrium or supersaturated phases due to high quenching speed.

Materials and Methods

Discussion

CoSb multiple secondaryphases phasesincluding includingFeSb

Conclusions