High performance Bi2Te3-based thermoelectric material and modules with a conversion efficiency of 5.2% under a temperature gradient of 250 K were synthesized by TIFS.
In this study, we prepared a series of Ag-doped PbSe bulk materials by a melting–quenching process combined with a subsequent spark plasma sintering process, and systematically investigated the doping effects of Ag on the thermoelectric properties. Ag substitution in the Pb site does not introduce resonant levels near the valence band edge or detectable change in the density of state in the vicinity of the Fermi level, but moves the Fermi level down and increases the carrier concentration to a maximum value of ∼4.7 × 1019 cm−3 which is still insufficient for heavily doped PbSe compounds. Nonetheless, the non-monotonic variation in carrier concentration with increasing Ag content indicates that Ag doping reaches the solution limit at ∼1.0% and the excessive Ag presumably acts as donors in the materials. Moreover, the large energy gap of the PbSe-based material wipes off significant ‘roll-over’ in the Seebeck coefficient at elevated temperatures which gives rise to high power factors, being comparable to p-type Te analogues. Consequently, the maximum ZT reaches ∼1.0 for the 1.5% Ag-doped samples with optimized carrier density, which is ∼70% improvement in comparison with an undoped sample and also superior to the commercialized p-type PbTe materials.
High performance Ge doped HMS compounds are synthesized by thermal explosion—a new method which paves the way for the mass production of HMS compounds and their large-scale industrial applications.
The Self-propagating-High-temperature-Synthesis (SHS) in combination with plasma activated sintering (PAS) is applied for the first time to SnTe-based thermoelectric materials and produces single-phase structures. Thermodynamic and kinetic parameters of the SHS process relevant to SnTe compounds were determined. InTe is supersaturated in InxSn1-xTe during the non-equilibriumSHSprocess.After annealing, doping SnTe by In gives rise to phase separation and the formation of InTe nanoinclusions which affect the carrier densityand, in turn, the transport properties. The presence of the InTe nanophase dramatically reduces the lattice thermal conductivity as low frequency heat carrying phonons are strongly scattered. Moreover, the ensuing deficiency of Te in the SnTe matrix gives rise to Te vacancies which reduce the density of hole carriers and thus enhance the Seebeck coefficient. Compared to samples synthesized by the traditional methods, the SHS-PAS technique shortens the synthesis time from several days to merely 15 min which bodes well for low cost mass production of SnTe-based materials. The phase separation process observed here for the first time effectively adjusts both the microstructure and the carrier density in SnTe-based materials and offers a new approach to optimize their thermoelectric properties.
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.