High thermoelectric performance of higher manganese silicides prepared by ultra-fast thermal explosion

Abstract

Higher manganese silicide (HMS) is an environmentally friendly p-type thermoelectric material with attractive performance and high stability in the intermediate temperature range (500–800 K). Due to the high melting point of HMS, the preparation methods reported previously always contain energy-intensive processes requiring long preparation periods and high cost. In this study, thermal explosion (TE) was adopted for a facile preparation of high performance HMS via a low cost route. During a typical thermal explosion (TE) process, nanostructured polycrystalline single-phase HMS powder with excellent thermoelectric performance is obtained in an ultra-short period of time (about 10 min). Dense bulk samples are then prepared by a rapid plasma activated sintering (PAS) technique. With Ge substituted in Si sites, a significant increase can be observed, which further enhanced the electrical properties. The results show that the Ge doped sample Mn(Ge_0.015Si_0.985)_1.75 prepared via the TE–PAS technique exhibits a maximum ZT of 0.62 at 840 K, which demonstrates that the TE–PAS technique is a versatile route for rapid fabrication of HMS and other thermoelectric materials.