Control of the Thermoelectric Properties of Mg2Sn Single Crystals via Point-Defect Engineering

Wataru Saito,Jing-Feng Li,Jinfeng Dong,Kei Hayashi,Yuzuru Miyazaki

doi:10.1038/s41598-020-58998-1

Wataru Saito, Jing-Feng Li + Show 3 more

Open Access

https://doi.org/10.1038/s41598-020-58998-1

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Journal: Scientific Reports	Publication Date: Feb 6, 2020
Citations: 36	License type: open-access

Affiliation: Tohoku University, Tsinghua University

Abstract

Mg2Sn is a potential thermoelectric (TE) material that can directly convert waste heat into electricity. In this study, Mg2Sn single-crystal ingots are prepared by melting under an Ar atmosphere. The prepared ingots contain Mg vacancies (VMg) as point defects, which results in the formation of two regions: an Mg2Sn single-crystal region without VMg (denoted as the single-crystal region) and a region containing VMg (denoted as the VMg region). The VMg region is embedded in the matrix of the single-crystal region. The interface between the VMg region and the single-crystal region is semi-coherent, which does not prevent electron carrier conduction but does increase phonon scattering. Furthermore, electron carrier concentration depends on the fraction of VMg, reflecting the acceptor characteristics of VMg. The maximum figure of merit zTmax of 1.4(1) × 10−2 is realised for the Mg2Sn single-crystal ingot by introducing VMg. These results demonstrate that the TE properties of Mg2Sn can be optimised via point-defect engineering.

Highlights

Thermoelectric (TE) materials, which are capable of converting waste heat into electricity, are expected to play a significant role in future energy utilisation and management[1,2]
The carrier concentration in a TE material can be optimised by tuning the fraction of point defects because they can act as acceptors or donors, which results in an increase in PF
Thermal conductivity can be reduced by introducing point defects because they can act as phonon scattering centres

Summary

Introduction

Thermoelectric (TE) materials, which are capable of converting waste heat into electricity, are expected to play a significant role in future energy utilisation and management[1,2]. CuKα) fractions of VMg and/or Mgi. Li et al.[23] reported that Mg2Sn single crystals exhibited anisotropic S values.

Results

Conclusion