Si-Based Materials for Thermoelectric Applications.

Sora-At Tanusilp,Ken Kurosaki

doi:10.3390/ma12121943

Sora-At Tanusilp, Ken Kurosaki

Open Access

https://doi.org/10.3390/ma12121943

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Journal: Materials	Publication Date: Jun 17, 2019
Citations: 11	License type: CC BY 4.0

Affiliation: Osaka University, University of Fukui, Kyoto University

Abstract

Si-based thermoelectric materials have attracted attention in recent decades with their advantages of low toxicity, low production costs, and high stability. Here, we report recent achievements on the synthesis and characterization of Si-based thermoelectric materials. In the first part, we show that bulk Si synthesized through a natural nanostructuring method exhibits an exceptionally high thermoelectric figure of merit zT value of 0.6 at 1050 K. In the second part, we show the synthesis and characterization of nanocomposites of Si and metal silicides including CrSi2, CoSi2, TiSi2, and VSi2. These are synthesized by the rapid-solidification melt-spinning (MS) technique. Through MS, we confirm that silicide precipitates are dispersed homogenously in the Si matrix with desired nanoscale sizes. In the final part, we show a promising new metal silicide of YbSi2 for thermoelectrics, which exhibits an exceptionally high power factor at room temperature.

Highlights

Thermoelectric (TE) devices have received attention for generating power from waste heat because they can directly convert temperature gradients into electricity
We report our recent accomplishments in the synthesis and characterization of
Our group has discovered that YbSi2−δ exhibits a high power factor of 2.2 mW·m−1−1·K−2 at room

Summary

Introduction

Thermoelectric (TE) devices have received attention for generating power from waste heat because they can directly convert temperature gradients into electricity. Si–Ge alloys are well-known as one of the best materials for TE power generation at high temperature [5,6], with a maximum zT value of around unity at 1100 K [6]. Bulk Si exhibits good electrical properties, its κlat is very high (>140 W·m−1 ·K−1 at 300 K for a non-doped single crystal [11,12]), yielding a low zT value of ~0.02 at maximum at 300 K [12]. The nanostructured bulk Si achieved by this method shows a greatly decreased κlat but no significant changes in the electron transport properties, yielding an exceptionally high zT value of ~0.6 at 1050 K [26]. We report on our discovery of the promising new metal silicide for TEs of YbSi2 , which exhibits a high power factor (S2 σ) at room temperature [35,36]

Bulk Nano-Si Thermoelectric Material

Synthesis

Scanning

Promising New Metal Silicide for TE Devices

Composition

The maximum

Summary