Nanostructured Thermoelectric Chalcogenides

Abstract

Thermoelectric materials are outstanding to transform temperature differences directly and reversibly into electrical voltage. Exploiting waste heat recovery as a source of power generation could help towards energy sustainability. Recently, the SnSe semiconductor was identified, in single-crystal form, as a mid-temperature thermoelectric material with record high figure of merit, high power factor and surprisingly low thermal conductivity. We describe the preparation of polycrystals of alloys of SnSe obtained by arc-melting; a rapid synthesis that results in strongly nanostructured samples with low thermal conductivity, advantageous for thermoelectricity, approaching the amorphous limit, around 0.3-0.5 W/mK. An initial screening of novel samples Sn 1−x M x Se, by alloying with 3d and 4d transition metals such as M = Mn, Y, Ag, Mo, Cd or Au, provides for a means to optimize the power factor. M=Mo, Ag, with excellent values, are described in detail with characterization by x-ray powder diffraction (XRD), scanning electron microscopy (SEM), and electronic and thermal transport measurements. Rietveld analysis of XRD data demonstrates near-perfect stoichiometries of the above-mentioned alloys. SEM analysis shows stacking of nanosized sheets, with large surfaces parallel to layered slabs. An apparatus was developed for the simultaneous measurement of the Seebeck coefficient and electric conductivity at elevated temperatures.

Structural Features, Anisotropic Thermal Expansion, and Thermoelectric Performance in Bulk Black Phosphorus Synthesized under High Pressure

“…Specific heat was calculated using the Dulong–Petit equation. High temperature measurements (300 up to 773 K) of the electrical resistivity were performed in the Van der Pauw geometry, while the Seebeck coefficient was measured in a homemade apparatus. , …”

“…High temperature measurements (300 up to 773 K) of the electrical resistivity were performed in the Van der Pauw geometry, while the Seebeck coefficient was measured in a homemade apparatus. 20,21 ■ RESULTS AND DISCUSSION Structural Properties. The crystal structure of black phosphorus was solved for the first time in 1935 by Hultgren et al and revised many times with different techniques.…”

Reduced Thermal Conductivity in Nanostructured AgSbTe2 Thermoelectric Material, Obtained by Arc-Melting

“…We have previously used the arc-melting technique to synthesize different chalcogenides and nanostructured compounds, such as PbTe [ 45 ], GeTe [ 46 , 47 , 48 ], Bi 2 Te 3 [ 49 , 50 , 51 ] or SnSe [ 39 , 52 , 53 , 54 , 55 , 56 , 57 , 58 ]. This synthesis method has the advantage to be very fast, compared to other techniques; the reaction itself happens in only a few seconds, and the entire process can be completed in several minutes.…”

Evidence of improvement in thermoelectric parameters of n-type Bi2Te3/graphite nanocomposite

“…[6][7][8][9][10][11][12] The increased phonon scattering at the newly formed interfaces between the matrix and dispersoids, results in a lowering of L. 5,7,[12][13][14][15][16] Furthermore, the additional interfaces in nanocomposites act as an energy barrier. By suppressing the transport of mid and long-wavelength phonons, which carry a considerable fraction of the heat, nanometer-sized grain boundaries can reduce the phonon contribution (L) to thermal conduction, leading to a substantial increase in ZT.…”