Abstract
Thermoelectric materials enables the harvest of waste heat and direct conversion into electricity. In search of high efficient thermoelectric materials, low thermal conductivity of a material is essential and critical. Here, we have theoretically investigated the lattice thermal conductivity and thermoelectric properties of layered intermetallic and based on the density functional theory and linearized Boltzmann equation with the single-mode relaxation-time approximation. It is found that both materials exhibit very low and anisotropic intrinsic lattice thermal conductivity. Despite the very low mass density and simple crystal structure of , its lattice thermal conductivities along and axes are only 1.77 and respectively at room temperatures. When Sn is replaced by the heavier element Pb, its lattice thermal conductivities decrease remarkably to 0.56 and respectively along and axes at room temperature. We show that the low lattice thermal conductivities of both materials are mainly due to their short phonon lifetimes and phonon mean free path. Combined with previous experimental measurements, the metallic cannot be a good thermoelectric material. However, we predict that the semiconducting is a potential room-temperature thermoelectric material with a considerable of 0.36 at 300 K. Our calculations not only imply that the intermetallic is a potential thermoelectric material, but also can motivate more theoretical and experimental works on the thermoelectric researches in simple layered intermetallic compounds.
1 More- Received 17 July 2018
- Revised 9 December 2018
DOI:https://doi.org/10.1103/PhysRevB.99.024310
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