Improved thermoelectric properties of Fe doped Si-rich higher manganese silicide

Sulfur Vacancy-Driven Band Splitting and Phonon Anharmonicity Enhance the Thermoelectric Performance in n-Type CuFeS2

“…Moreover, a high-performance TE material must possess a high σ, and a large S with low total thermal conductivity, κ total = κ el + κ latt , in order to yield a high zT . However, attaining a high zT is cumbersome because S , σ, and κ el are interdependent on the carrier concentration. − In this regard, numerous strategies have been implemented to increase the numerator part, power factor ( S 2 σ), such as the energy filtering of minority carriers, − creating resonant states around the Fermi level ( E F ), − and facilitating the convergence of valence subbands. − Alternatively, the thermal conductivity could also be effectively reduced by introducing nano/meso-precipitates, − grain boundary phonon scattering, − and intrinsic bond anharmonicity − in the state-of-the-art materials, such as Bi 2 Te 3 , , PbTe, , SnSe, , GeTe, , and have been recently promoted as highly efficient, cost-effective, and environmentally friendly TE materials belonging to classes, namely silicides, − skutterudites, , and antimonides. − On the other hand, high-performance TE materials comprise toxic, expensive, or scarce elements in their composition, which resulted in the hunt for alternate earth-abundant materials containing inexpensive elements, leading to the discovery of ternary and quaternary sulfides. While p -type sulfides show enhanced figure of merit, n- type equivalents, however, remain scarce.…”

Lattice anharmonicity in charge compensated higher manganese silicide single crystals

“…22,24,25 However in comparison, the hole concentration of pristine 17 MnSi g ∼2 (±1) × 10 21 cm −3 and V-substituted 24,25 MnSi g ∼4 (±1) × 10 21 cm −3 is relatively higher than the carrier concentration range 10 19 -10 21 cm −3 at which power factor for the most state-of-the-art TE materials optimizes. 7 Thus, optimization of hole concentration in HMS crystals by some degree of hole compensation may enhance the power factor, which has been previously investigated by using electron dopants such as Fe, [26][27][28][29][30][31][32] Co, 32,33 and Ru 15,34 at the [Mn]subsystem of MnSi g . Amongst electron dopants, Fe-substitution of HMS displays high solubility in solid solution and can bring a considerable change in carrier concentration, wherein the p-n transition in electrical conduction was observed above 20% Fesubstitution in HMS.…”