Significant Enhancement of the Thermoelectric Performance of Higher Manganese Silicide by Incorporating MnTe Nanophase Derived from Te Nanowire

Abstract

Higher manganese silicide (HMS) is a naturally abundant, eco-friendly, and low-cost p-type thermoelectric semiconductor with high power factor (PF); however, its figure of merit (ZT) is very low due to an intrinsically high thermal conductivity (κ). It is also difficult to synthesize a HMS single phase without MnSi or Si second phase, which generally leads to a significant decrease of the PF and/or increased κ. In this study, pure HMS was obtained via wet ball milling in combination with spark plasma sintering. A further p-type MnTe, with high Seebeck coefficient (S) and low κ, was incorporated into the HMS matrix to form MnTe/HMS composites. To effectively decrease κ, while simultaneously enhancing the electrical conductivity, Te nanowires of ∼35 nm in diameter were synthesized with a solution phase method and subsequently embedded to HMS to form MnTe/ HMS nano/bulk structures. The incorporation of Te nanowires led to a 38% reduction of κ in addition to a slight increase of S. Finally, the ZT max of MnTe/HMS nano/bulk composites increased by ∼71% from 0.41 to 0.70. This study demonstrates a unique and facile method to boost the ZT of HMS to a high level, which is also applicable to other thermoelectric materials.

Eco‐Friendly Higher Manganese Silicide Thermoelectric Materials: Progress and Future Challenges

“…[36,55,56,60,61,[81][82][83] In recent years, it has developped nontoxic, low-cost thermoelectric materials as substitutes for current high-cost and high zT thermoelectric materials to draw real industrial attentions. Inspired by this, many promising earth-abundant and less-toxic or nontoxic thermoelectric materials have been explored, including lead-free SnTe, [5,[84][85][86] Cu 2 Se, [87,88] Cu 12 Sb 4 S 13 , [89] Cu 2 ZnGeSe 4 , [90] Cu 2 CdSnSe 4 , [91] especially silicides, [45,92] including Mg 2 Si [46] and higher manganese silicide (HMS), [63,64,93] composed earth abundant and eco-friendly Mn and Si.…”

Thermoelectric, Magnetic, and Mechanical Characteristics of Antiferromagnetic Manganese Telluride Reinforced with Graphene Nanoplates

“…The Mn reaction with carbon consumes Mn, leading to Te-rich domains that favor the formation of MnTe 2 , as confirmed by the XRD peak at 2θ ¼ 32 ( Figure 3). The formation of the MnTe 2 phase can be explained by thermodynamic considerations [73,74] based on three reaction steps for the formation of MnTe alloy in the current study: 1) 2Mnþ2Te ! MnTe 2 þMnþ Q 1 @ mechanical alloying and milling (MnTe 2 standard heat of formation ¼ À26.4 kcal mol À1 ); [75] 2) MnTe 2 !…”

Thermoelectrics: From history, a window to the future

“…Gelbstein et al described nanostructured ntype Mg 2 Si 1-x Sn x and p-type HMSs with high maximal zT values respectively of 1.1 and 0.6 at 723 K [292]. In 2017 Te nanowires embedded to HMS were shown to increase zT from 0.41 to 0.70 at 800 K [293].…”