Compositional Fluctuations Mediated by Excess Tellurium in Bismuth Antimony Telluride Nanocomposites Yield High Thermoelectric Performance

Abstract

A high thermoelectric figure of merit (ZT) in state-of-the-art bismuth antimony telluride (BST) composites was attained by an excess telluriumassisted liquid-phase compaction approach. Herein, we report a maximum ZT of ≈ 1.4 at 500 K attained for BST bulk nanocomposites fabricated by spark plasma sintering of colloidally synthesized (Bi,Sb) 2 Te 3 platelets and Te-rich rods. The Terich nanodomains and antimony precipitation during sintering result in compositional fluctuations and atomic ordering within the BST−Te eutectic microstructure, which provides additional phonon scattering and hole contributions. The electrical transport measurement and theoretical calculations corroborate the altered free carrier density via lattice defects and atomic ordering under Te-rich conditions, resulting in a higher power factor. Microstructural studies suggest that reduction in lattice thermal conductivity is due to composite interfaces and defects in the closely packed (Bi,Sb) 2 Te 3 matrix with unevenly distributed Sband Te-rich nanodomains. This work provides an unconventional chemical synthesis route with large scalability for developing high-performance chalcogenide-based bulk nanocomposites for thermoelectric applications.

Recent Advances in the Nanomaterials, Design, Fabrication Approaches of Thermoelectric Nanogenerators for Various Applications

“…Alloys of tellurium-based, often formed by doping with metals like selenium [24] and antimony, [62] have been shown to exhibit reduced thermal conductivity because of increased Figure 3. Schematic diagram of spark plasma sintering used to recover waste Bi 2 Te 3 alloy material.…”

“…Alloys of tellurium‐based, often formed by doping with metals like selenium [ 24 ] and antimony, [ 62 ] have been shown to exhibit reduced thermal conductivity because of increased crystal defects. [ 63 ] For example, Zhu et al.…”

Large-Scale Colloidal Synthesis of Chalcogenides for Thermoelectric Applications

“…The nanoparticles were then subjected to SPS densification, which afforded nanostructured n -type Bi 2 Te 2.7 Se 0.3 material exhibiting a maximum ZT ≈ 1 at 373 K with an average ZT ≈ 0.93 (300–473 K). More recently, we prepared composite (Bi,Sb) 2 Te 3 nanoplatelets and Te-rich nanorods by colloidal synthesis . After SPS consolidation, the resultant Bi-based TE material exhibits a maximum ZT ≈ 1.4 at 500 K. Considering the versatile synthetic potential of our colloidal synthesis toward chalcogenides, we were interested in expanding the scope of this synthesis beyond the preparation of nanostructured Bi-based TE materials.…”

A mechanistic view of defect engineered VFeSb half-Heusler alloys

“…[1][2][3] Owing to the ubiquitous nature of defects and their significant impact on the physical properties of solids, defect engineering in TEs provides a unique ability to decouple their thermal and electrical transport properties, synergistically. For example, defect-related spin tuning, 1,4 defect-induced energy filtering, [5][6][7] vacancy-mediated atom or charge transfer, [8][9][10][11] surface distortion, 12,13 and dislocations [14][15][16] are actively explored approaches in TE material research, which appear to be promising in overcoming the limitations of prevailing electronic and phonon structure optimization strategies. The presence of defects is categorized by their dimensionality in a material's microstructure, such as point defects (such as vacancies, interstitials, and antisites), dislocations, planar defects (such as twin boundaries, stacking faults, and grain boundaries), and volume defects (mainly precipitates and voids).…”