This paper presents tables of key thermoelectric properties, which define thermoelectric conversion efficiency, for a wide range of inorganic materials. The 12 families of materials included in these tables are primarily selected on the basis of well established, internationally-recognised performance and their promise for current and future applications: Tellurides, Skutterudites, Half Heuslers, Zintls, Mg-Sb Antimonides, Clathrates, FeGa3–type materials, Actinides and Lanthanides, Oxides, Sulfides, Selenides, Silicides, Borides and Carbides. As thermoelectric properties vary with temperature, data are presented at room temperature to enable ready comparison, and also at a higher temperature appropriate to peak performance. An individual table of data and commentary are provided for each family of materials plus source references for all the data.

The thermal conductivity of Cu2Te is around 4 W m−1 K−1 at 300 K with low Cp values.

Superionic Cu 2-x Te (CT) is an interesting and emerging p-type thermoelectric (TE) material due to the existence of various polymorphic phases and crystal structures, which undergo several structural phase transitions. On the basis of the stoichiometry of the CT compounds, the structure parameters, the carrier concentration (n p ), and the thermal conductivity (κ) can be modulated for optimum TE performance. Further, the understanding of the fundamental properties and their impact on TE parameters is not well understood because of their complex structures. We have investigated the vibrational properties of CT compounds such as Cu 1.25 Te (CT1.25), Cu 1.6 Te (CT1.6), and Cu 2 Te (CT2) using temperature dependent Raman studies in the temperature range of 300−773 K. Several structural phases are probed through remarkably distinct spectra for the CT compounds. The temperature transitions are complex such as (i) eutectic melting into CuTe and Te for both CT1.6 (above ∼593 K) and CT1.25 (above ∼613 K) and (ii) the structural transition from trigonal to orthorhombic and cubic phase for CT2 (above ∼553 K), which are strongly manifested in the Raman study. Further, the role of n p in the Raman spectra has also been investigated. The intensity of the Raman modes (>100 cm −1 ) showed strong n p dependence due to strong plasmon−phonon coupling. The analysis of full width at half-maximum (fwhm) of Raman peaks and qualitative estimation of phonon lifetime (τ i ) showed that CT2 has the minimum lattice thermal conductivity.

Owing to the high thermoelectric (TE) conversion efficiency, low cost, and environmental friendliness Mg 2 Si 0.3 Sn 0.7 solid solution has emerged as the material of choice for the n-leg of a TE generator for midtemperature (room temperature to 800 K) applications. Dimensionless TE figure-of-merit (ZT) values of 1.3 (at 700 K) have been reported in this compound when optimally doped. High ZT values in this compound are due to a combination of improved electrical properties (band convergence effect) and reduced lattice thermal conductivity (alloy scattering of phonons). Here we demonstrate that the TE performance in this solid solution can be improved further (ZT max = 1.7 at T = 673 K, which is a record in silicide-based TE materials) by enhancing phonon scattering with embedded nanoprecipitates. The high ZT values are obtained when Mg 2 Si 0.3 Sn 0.7 is codoped with Bi and Cr. While Bi helps in optimizing the electrical transport properties, Cr results in formation of nanoprecipitates. Transmission electron microscopy (TEM) studies indicate embedded nanoprecipitates rich in elemental Cr and Sn. The nanoprecipitates also result in a strained interface as confirmed from high-resolution TEM (HRTEM) and grazing incidence XRD (GIXRD) studies. This results in an ∼15% reduction in the lattice thermal conductivity (κ L ) compared to the only Bi-doped sample while retaining similar power factor (S 2 σ) values. The overall effect is a ZT eng value of 0.73, which corresponds to a conversion efficiency (η) of 12% with the cold side temperature of 323 K and a ΔT = 350 K.

This article reports luminescence studies on wet-chemical route prepared YVO 4 :Er 3 ∕Yb 3 microdisc phosphor. The 980 nm laser excited upconversion (UC) emission intensity ratio of green to red bands is found too high to neglect the contribution from the red emission band, which is not observed normally in Er 3 ∕Yb 3 -doped materials. The red emission is also found absent in the downconversion emission under excitation at 316 nm. The variation of UC intensities with external temperature exhibits a well-fashioned pattern, which suggests that the 2 H 11∕2 and 4 S 3∕2 levels of Er 3 ion are thermally coupled. The YVO 4 :Er 3 ∕Yb 3 phosphor has shown outstanding temperature-sensing behavior with maximum sensitivity of 0.0117 K −1 at 400 K. This material is also employed to develop a latent fingerprint in green color. Furthermore, the present phosphor could be useful for solar cell concentrators, drug delivery, and disease therapy applications.

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