Materials and Methods 1. Sample preparation method Tl-doped PbTe was made by direct reaction of appropriate amounts of Pb, Te, and Tl 2 Te in a fused-silica tube sealed under a vacuum. Each sample was briefly melted at 1273 K for 24 h and lightly shaken to ensure homogeneity of the liquid, then furnace cooled to 800 K and annealed for 1 week. The obtained ingot was crushed into fine powder and hot-pressed at 803 K for 2 hours under a flowing 4% H 2-Ar atmosphere. The final form of each polycrystalline sample was a 2mm thick disk about 10 mm in diameter. Phase purity was checked by powder X-ray diffraction. No impurity phases were found in the XRD patterns, indicating that all added Tl was dissolved in PbTe. The purities of all starting materials were at least 99.99%. The samples were stable in air at room temperature.
We report measurements of the thermal conductivity of high-quality crystals of the cubic I-V-VI2 semiconductors AgSbTe2 and AgBiSe2. The thermal conductivity is temperature independent from 80 to 300 K at a value of approximately 0.70 W/mK. Heat conduction is dominated by the lattice term, which we show is limited by umklapp and normal phonon-phonon scattering processes to a value that corresponds to the minimum possible, where the phonon mean free path equals the interatomic distance. Minimum thermal conductivity in cubic I-V-VI2 semiconductors is due to an extreme anharmonicity of the lattice vibrational spectrum that gives rise to a high Grüneisen parameter and strong phonon-phonon interactions. Members of this family of compounds are therefore most promising for thermoelectric applications, particularly as p-type materials.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.