Quaternary thermoelectric materials: Synthesis, microstructure and thermoelectric properties of the (Bi,Sb)2(Te,Se)3 alloys

Abstract

High-quality quaternary Bi 0.5 Sb 1.5 Te 3-x Se x (BSTS) alloys with x=0.3, 0.5 and 0.75 are successfully synthesized in 25 min by high pressure and high temperature (HPHT) method. Due to the effects of synthesis pressure and Se doping, the texture and microstructure exhibit abundant distorted layers and lattice defects. The unique triangular nanoplates can be obtained in the microstructures by HPHT method without any substrates, suggesting that Bi 0.5 Sb 1.5 Te 3-x Se x has a nature of the epitaxial growth. The thermoelectric transport properties are characterized in detail, revealing an evident correlation with the amount of Se doping. As a result, a maximum ZT value of 0.95 is achieved at 503K from the as-prepared Bi 0.5 Sb 1.5 Te 2.7 Se 0.3 alloys. Additionally, Raman spectra are conducted and then indicate that Se doping contents have an important influence on the lattice vibrations and lattice structures of quaternary (Bi,Sb) 2 (Te,Se) 3 alloys.

Synergistically Optimized Electron and Phonon Transport of Polycrystalline BiCuSeO via Pb and Yb Co-Doping

“…The Seebeck coefficient decreases with increasing Pb&Yb concentration despite a slight fluctuation in the Seebeck coefficient observed for light doping, which may be attributed to the synergistic effect of dual doping on the carrier concentration and the effective mass. The electrical resistivity of all the samples increases monotonously with temperature, as shown in Figure B, suggesting a transport behavior for metals and degenerate semiconductors, − consistent with the temperature dependence of the Seebeck coefficient. In contrast to the electrical resistivity of pristine BiCuSeO, a remarkable decrease of electrical resistivity has been recorded in Pb&Yb co-doped BiCuSeO, which is over 3 times less than that of pristine BiCuSeO over the measured temperature range.…”

A review on recent developments of thermoelectric materials for room-temperature applications

“…For selecting an appropriate dopant, electronegativity of the replaced element should be taken into consideration. Thus, Wang et al [34] Instead of spark plasma method, Guo et al [36] employed high pressure and high temperature method to synthesize Bi0.5Sb1.5Te3xSex alloys (x=0.3, 0.5 and 0.75). The results revealed that synthesis pressure and Se doping caused abundant distorted layers and lattice defects.…”

Multiple Roles of Unconventional Heteroatom Dopants in Chalcogenide Thermoelectrics: The Influence of Nb on Transport and Defects in Bi2Te3

“…Strategies such as energy filtering, band engineering, and doping , are among several that have been repeatedly demonstrated to improve the thermoelectric performance of Bi 2 Te 3 -based alloys. Moreover, the physical sensitivity of Bi 2 Te 3 to different synthesis and processing routes (such as spark plasma sintering, , self-propagating high-temperature synthesis, , high-pressure sintering, , etc.) has provided almost boundless opportunities to modulate crystal structure, texture, and microstructure from large single crystals to engineered nanoarchitectures.…”