Enhanced thermoelectric power factor of Re-substituted higher manganese silicides with small islands of MnSi secondary phase

Abstract

Higher manganese silicides (HMS) are promising thermoelectric materials owing to the abundance of the constituent elements in the earth crust, environmental friendliness and good chemical stability at high temperatures. However, the metallic MnSi layers with a lateral size as large as B50 mm are formed in the melt-grown HMS samples. These large MnSi layers are characterized with relatively high electrical and thermal conductivities and low Seebeck coefficient, which can degrade the thermoelectric performance of the melt-grown samples. Here, we report the synthesis and thermoelectric properties of Re-substituted HMS with relatively small-size MnSi platelets via melt-quenching, followed by ball-milling, and consolidated by spark plasma sintering. As compared to the samples prepared by either solid-state reaction or mechanical alloying, the reduced lateral size of MnSi in the quenched sample leads to an increased carrier concentration without a reduction in the carrier mobility according to our electrical transport measurements. As a result, the thermoelectric power factor is increased to 1.9 AE 0.2 Â 10 À3 W m À1 K À2 at 860 K, which is about 20% higher than that of the sample prepared by solid-state reaction. In addition, the lattice thermal conductivity of the quenched sample remains nearly the same as the samples prepared by two other synthesis methods. Therefore, a figure-of-merit ZT of 0.64 AE 0.08 at 823 K is obtained for the quenched sample, compared to 0.57 AE 0.07 and 0.26 AE 0.03 obtained from the two other samples prepared by different methods.

Promising and Eco‐Friendly Cu2X‐Based Thermoelectric Materials: Progress and Applications

“…Further studies have enhanced the peak zT values of GeTe‐based thermoelectric materials to a level higher than 2 . Under this temperature range (from ≈650 to ≈800 K), other p‐type thermoelectric materials, such as SnSe and higher manganese silicide have also drawn extensive research interests due to either low cost or high performance. Both Zhao et al and Liu et al have reported the peak zT value of SnSe can be higher than 2 when the temperature is above 800 K. Meanwhile, most other results suggest the peak zT values of SnSe are at the temperature range lower than 800 K .…”

“…Mater. 2020, 32,1905703 [39,61,102,103] AgSeTe 2 , [104,105] GeTe, [106][107][108][109][110][111][112][113] SnSe, [34,35,40,45,47,[88][89][90]92,114] higher manganese silicide (HMS), [115][116][117] Cu 2 X (X = Te, Se, and S), [2,72,99,[118][119][120][121][122][123][124][125][126][127][128][129] PbX (X = Te, Se, and S), [30,[63][64][65][130][131][132]...…”

“…a) Peak zT values of state‐of‐the‐art p‐type thermoelectric materials as a function of temperature ( T ), including Bi 0.5 Sb 1.5 Te 3 , AgSeTe 2 , GeTe, SnSe, higher manganese silicide (HMS), Cu 2 X (X = Te, Se, and S), PbX (X = Te, Se, and S), SnTe, BiCuSeO, and half Heusler‐based ones. b) Peak zT values of state‐of‐the‐art Cu 2 X‐based thermoelectric materials and their derivatives as a function of publication year.…”

Glass-like thermal conductivity in nanostructures of a complex anisotropic crystal

“…In this article, we report a combined experimental and theoretical study of the size effects on thermal transport in ∼20 nm thick ribbon structures of a representative complex crystal, higher manganese silicide (HMS), which is one of the leading thermoelectric materials made from earth-abundant, non-toxic elements 20,21 . Because of an advance in making clean electrical contact to suspended nanostructures, we are able to conduct four-probe thermoelectric measurements of the suspended nanoribbon and obtain the intrinsic thermal conductivity, which is considerably suppressed compared to the bulk values.…”

Development and understanding of solvothermal synthesized copper chalcogenide thermoelectric materials

“…[106][107][108][109][110][111][112][113] Further studies have enhanced the peak zT values of GeTe-based thermoelectric materials to a level higher than 2. [108,[110][111][112] Under this temperature range (from ~650 to ~800 K), other p-type thermoelectric materials, such as SnSe [34, 35, 40, 45, 47, 88-90, 92, 114] and Higher Manganese Silicide [115][116][117] have also drawn extensive research interests due to either low-cost or high-performance. Both…”