This review discusses about the crystal structure, chemical bonding, and the electronic band structure of tetrahedrite materials. Also, this review outlines the effect of different doping elements on the thermoelectric properties of tetrahedrite materials.

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A systematic study of structural, microstructural, and thermoelectric properties of bulk PbTe doped with indium (In) alone and co-doped with both indium and iodine (I) has been done. X-ray diffraction results showed all the samples to be of single phase. Scanning electron microscopy (SEM) results revealed the particle sizes to be in the range of micrometers, while high resolution transmission electron microscopy was used to investigate distinct microstructural features such as interfaces, grain boundaries, and strain field domains. Hall measurement at 300 K revealed the carrier concentration $10 19 cm À3 showing the degenerate nature which was further seen in the electrical resistivity of samples, which increased with rising temperature. Seebeck coefficient indicated that all samples were n-type semiconductors with electrons as the majority carriers throughout the temperature range. A maximum power factor $25 lW cm À1 K À2 for all In doped samples and Pb 0.998 In 0.003 Te 1.000 I 0.003 was observed at 700 K. Doping leads to a reduction in the total thermal conductivity due to enhanced phonon scattering by mass fluctuations and distinct microstructure features such as interfaces, grain boundaries, and strain field domains. The highest zT of 1.12 at 773 K for In doped samples and a zT of 1.1 at 770 K for In and I co-doped samples were obtained.

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High-output-power densities from molecular beam epitaxy grown n-and p-type PbTeSe-based thermoelectrics via improved contact metallization J. Appl. Phys. 111, 104501 (2012) Lead telluride and its alloys are well known for their thermoelectric applications. Here, a systematic study of PbTe 1-y Se y alloys doped with indium has been done. The powder X-Ray diffraction combined with Rietveld analysis confirmed the polycrystalline single phase nature of the samples, while microstructural analysis with scanning electron microscope results showed densification of samples and presence of micrometer sized particles. The temperature dependent transport properties showed that in these alloys, indium neither pinned the Fermi level as it does in PbTe, nor acted as a resonant dopant as in SnTe. At high temperatures, bipolar effect was observed which restricted the zT to 0.66 at 800 K for the sample with 30% Se content. V C 2014 AIP Publishing LLC.