Issue 20, 2016

In situ nanostructure design leading to a high figure of merit in an eco-friendly stable Mg2Si0.30Sn0.70 solid solution

Abstract

The relationship between the temperature and the composition as well as the microstructure of a Sb-doped Mg2Si0.30Sn0.70 solid solution was systematically studied according to the Mg2Si–Mg2Sn pseudo-binary phase diagram. This work shows that the composition, distribution pattern, and fraction of in situ nanostructures can be controlled by the heat treatment carried out at a specific peritectic reaction temperature. A large number of in situ nanoprecipitates were observed when the sample was quenched at 900 K or 1130 K. However, quenching at 900 K resulted in the formation of agglomerates while quenching at 1130 K yielded a more even dispersion of nanoprecipitates. Monochromatic X-ray studies, back-scattering images and HRTEM results showed that the composition of the nanoprecipitates when quenched at 900 K was the Mg2Si-rich phase, while the nanostructure was the Mg2Sn-rich phase when quenched at 1130 K. The lattice thermal conductivity decreased dramatically due to the well distributed Mg2Sn-rich nanoprecipitates, and the maximum ZT of about 1.2 was achieved at around 750 K. Moreover, the average value of the figure of merit ZTaverage reached about 0.9 in the range of 300–800 K, about a 15% higher value than in the sample composed of Mg2Si-rich nano-agglomerates. This study demonstrates that carrying out heat treatments at the phase transformation temperatures is a simple and controllable method to design and form in situ nanostructures, which is of vital importance in the fabrication of nanocomposites and optimization of the thermoelectric performance.

Graphical abstract: In situ nanostructure design leading to a high figure of merit in an eco-friendly stable Mg2Si0.30Sn0.70 solid solution

Supplementary files

Article information

Article type
Paper
Submitted
19 Dec 2015
Accepted
04 Feb 2016
First published
04 Feb 2016

RSC Adv., 2016,6, 16824-16831

In situ nanostructure design leading to a high figure of merit in an eco-friendly stable Mg2Si0.30Sn0.70 solid solution

K. Yin, X. Su, Y. Yan, C. Uher and X. Tang, RSC Adv., 2016, 6, 16824 DOI: 10.1039/C5RA27171A

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements