Reinforced bond covalency and multiscale hierarchical architecture to high performance eco-friendly MnTe-based thermoelectric materials

In Situ Reaction Induced Core–Shell Structure to Ultralow κlat and High Thermoelectric Performance of SnTe

“…The mechanism behind this reaction can be illustrated in the perspective of chemical bonding; it is known that the electronegativity of Te is stronger than Sb, while the metallicity of Zn is stronger than that of Sn, so the chemical bond between Zn and Te is the strongest among the bonds of Zn, Sn, Sb elements with Te. And the calculated Gibbs free energy (−44.5 kJ mol −1 ), as listed in Table S1 in the Supporting Information, further confirms that the reaction is favorable in thermodynamics 15. Therefore, during the SPS process, the Zn 2+ in ZnSb nanoparticles (NP) gradually combines with Te 2− in SnTe matrix and results in the formation of the Sb@ZnTe core–shell structures, which is significantly conducive to the TE performance of SnTe and will be detailed below.…”

“…And the calculated Gibbs free energy (−44.5 kJ mol −1 ), as listed in Table S1 in the Supporting Information, further confirms that the reaction is favorable in thermodynamics. [15] Therefore, during the SPS process, the Zn 2+ in ZnSb nanoparticles (NP) gradually combines with Te 2− in SnTe matrix and results in the formation of the Sb@ ZnTe core-shell structures, which is significantly conducive to the TE performance of SnTe and will be detailed below.…”

Physical Insights on the Lattice Softening Driven Mid‐Temperature Range Thermoelectrics of Ti/Zr‐Inserted SnTe—An Outlook Beyond the Horizons of Conventional Phonon Scattering and Excavation of Heikes’ Equation for Estimating Carrier Properties

“…[26][27][28][29][30][31] Due to larger anharmonicity and effective phonon scattering, PbTe exhibits lower thermal conductivity than SnTe. [32][33][34][35] Various attempts and strategies have been made in the past to improve the thermoelectric performance in SnTe, which includes selfcompensation in the composition with some additional Sn content; [36,37] electronic bandstructure engineering-fostering resonance state in the vicinity of fermi-level (mostly induced by In as a dopant in SnTe), [27,38] simultaneous increase of principal bandgap and convergence of the light hole and heavy hole valence bands (realized with dopants such as Cd, Hg, Mn, Mg, Ca, and few more), [27,29,36,37,[39][40][41][42][43][44] and this also includes valence band inversion or crossing effects; and a diverse nano-structuration approaches to engineer the dense interstitials, stacking faults, point defects, nano-precipitates and semi-coherent interfaces, dislocations, strain clusters, and so forth, [45][46][47][48][49][50][51][52] (by alloying with Cu 2 Te, CdS, SrTe, ZnS, and a few more). [53] All these approaches and dopants in SnTe, though they yielded an improved thermoelectric performance (zT max > 1), are limited for any practical applications, as their improved performance happened only at higher temperature ranges (usually between 823 and 873 K, or higher) for SnTe-based materials.…”

Paramagnon drag in high thermoelectric figure of merit Li-doped MnTe

“…We worked with Li-doped MnTe, a p-type AFM semiconductor with an ordering temperature T N ~ 307 K, a Curie-Weiss temperature of T C ~ −585 K ( 7 ), and a direct band gap of Eg ~ 1.2 eV. MnTe crystallizes in the hexagonal NiAs structure and is known to be a good thermoelectric material ( 8 , 9 , 10 ). Previous work ( 2 ) on resistivity, Hall, and thermopower identified a strong magnon-drag effect in the AFM state, but no predictive model was given, and the thermopower in the paramagnetic (PM) regime remained unexplained ( 11 , 12 ).…”