| Abstrakt: |
Thermoelectric materials are best known for their prowess to transform the environment's waste heat into electricity. In an endeavor to explore new thermoelectric prospects, in the present study, we investigate K 2 AuBi using density functional theory-based first-principles simulations. From our simulations, we find an intrinsically low lattice thermal conductivity of 0.43 W m − 1 K − 1 at 300 K in K 2 AuBi. Based on our detailed analysis, we find the reasons for such a low value of lattice thermal conductivity as, low phonon group velocities, short phonon lifetimes, anharmonicity in the lattice vibrations, and significant mean square displacements of K and Au atoms. The large mean square displacements hint at weak bonding and anharmonicity in the lattice vibrations, favoring more phonons scattering. We also find that the vibrations of K-atoms can be related to rattlers, conducive to low lattice thermal conductivity. Our simulations predict a high value, ∼ 784 μ V K − 1 , of Seebeck coefficient at 700 K on account of the large density of states in the vicinity of Fermi level. Combining our computed lattice thermal conductivity with electrical transport properties, we obtain a high figure of merit, Z T ∼ 1.04, at 700 K in K 2 AuBi. [ABSTRACT FROM AUTHOR] |
