In this review, we describe the creation of a large database of thermoelectric materials prepared by abstracting information from over 100 publications. The database has over 18 000 data points from multiple classes of compounds, whose relevant properties have been measured at several temperatures. Appropriate visualization of the data immediately allows certain insights to be gained with regard to the property space of plausible thermoelectric materials. Of particular note is that any candidate material needs to display an electrical resistivity value that is close to 1 mΩ cm at 300 K, that is, samples should be significantly more conductive than the Mott minimum metallic conductivity. The Herfindahl–Hirschman index, a commonly accepted measure of market concentration, has been calculated from geological data (known elemental reserves) and geopolitical data (elemental production) for much of the periodic table. The visualization strategy employed here allows rapid sorting of thermoelectric compositions w...

/pdf/data-driven-review-of-thermoelectric-materials-performance-1kg3380nsh.pdf

Data-Driven Review of Thermoelectric Materials: Performance and Resource Considerations

Magnesium silicide and related alloys are attractive for thermoelectric applications due to their low toxicity, thermal stability, low density, relative abundance and low cost of production. Earlier work on the synthesis of Mg2Siviahigh energy ball milling resulted in incomplete product formation, oxide impurities, and contamination from milling media. Here we present an improved solid-state synthesis of n-type magnesium silicide using the mechanochemical technique of high energy ball milling of the elements followed by high pressure sintering using hot uniaxial compaction. This robust synthetic method permits a detailed investigation of thermoelectric properties as a function of Bi doping. The thermoelectric properties of Mg2Si1−xBix (0 ≤ x ≤ 0.021) samples are characterized from 300 K to 775 K. These results are analyzed within a single parabolic band (SPB) model to determine the effective conduction band parameters and identify regimes of non-SPB behavior.

Mechanochemical synthesis and thermoelectric properties of high quality magnesium silicide

https://iopscience.iop.org/article/10.7567/JJAP.56.05DA04/pdf

Thermoelectric silicides: A review

The low crustal abundance of materials such as tellurium (Te) (0.001 ppm by weight), antimony (Sb) (0.2 ppm), and germanium (Ge) (1.4 ppm) contributes to their price volatility as applications (competing with thermoelectrics) continue to grow, for example, cadmium telluride photovoltaics, antimony-lead alloy for batteries, and Ge for fiber optics and infrared optical technologies. Previous consideration of material scarcity has focused on Te-based thermoelectrics. Here, we broaden the analysis to include recent high-figure-of-merit (ZT) materials such as skutterudites, Zintl phase compounds, and clathrates that employ Sb, ytterbium (2.8 ppm), and Ge. The maximum demonstrated ZT for each particular alloy exhibits an empirical dependence on the crustal abundance, A, such that ZT = A−b, where b is in the range from 0.05 to 0.10. This analysis shows that no material with crustal abundance of 30 ppm (~4 × 1018 metric tons) has ZT greater than 0.8.

Trend for Thermoelectric Materials and Their Earth Abundance

Thermoelectric properties of materials near the band crossing line in Mg2Sn–Mg2Ge–Mg2Si system

Thermoelectric properties and electronic structure of p-type Mg2Si and Mg2Si0.6Ge0.4 compounds doped with Ga

Mg2Si1−xGex compounds were prepared from pure elements by melting in tantalum crucibles. The reaction was conducted under an inert gas in a special laboratory setup. Samples for thermoelectric measurements were formed by hot pressing. Structure and phase composition of the obtained materials were investigated by x-ray diffraction (XRD). Morphology and chemical composition were examined by scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS), respectively. Thermoelectric properties, i.e., the Seebeck coefficient, the electrical conductivity, and the thermal conductivity, were measured in the temperature range of 500 K to 900 K. The effect of Bi and Ag doping on the thermoelectric performance of Mg-Si-Ge ternary compounds was investigated. The electronic structures of binary compounds were calculated using the Korringa–Kohn–Rostoker (KKR) method. The effects of disorder, including Ge substitution and Bi or Ag doping, were accounted for in the KKR method with coherent potential approximation calculations. The thermoelectric properties of doped Mg2Si1−xGex are discussed with reference to computed density of states as well as the complex energy band structure.

G. Pont

Papers

Thermoelectric properties and electronic structure of p-type Mg2Si and Mg2Si0.6Ge0.4 compounds doped with Ga

Thermoelectric Properties and Electronic Structure of Bi- and Ag-Doped Mg2Si1-xGex Compounds