Melt-Centrifuged (Bi,Sb)<sub>2</sub> Te<sub>3</sub> : Engineering Microstructure toward High Thermoelectric Efficiency.
basic_science · Level V
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- Record sourced from PubMed, PMID 29984538.
- Also identified by DOI 10.1002/adma.201802016.
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Abstract
Microstructure engineering is an effective strategy to reduce lattice thermal conductivity (κ<sub>l</sub> ) and enhance the thermoelectric figure of merit (zT). Through a new process based on melt-centrifugation to squeeze out excess eutectic liquid, microstructure modulation is realized to manipulate the formation of dislocations and clean grain boundaries, resulting in a porous network with a platelet structure. In this way, phonon transport is strongly disrupted by a combination of porosity, pore surfaces/junctions, grain boundaries, and lattice dislocations. These collectively result in a ≈60% reduction of κ<sub>l</sub> compared to zone melted ingot, while the charge carriers remain relatively mobile across the liquid-fused grains. This porous material displays a zT value of 1.2, which is higher than fully dense conventional zone melted ingots and hot pressed (Bi,Sb)<sub>2</sub> Te<sub>3</sub> alloys. A segmented leg of melt-centrifuged Bi<sub>0.5</sub> Sb<sub>1.5</sub> Te<sub>3</sub> and Bi<sub>0.3</sub> Sb<sub>1.7</sub> Te<sub>3</sub> could produce a high device ZT exceeding 1.0 over the whole temperature range of 323-523 K and an efficiency up to 9%. The present work demonstrates a method for synthesizing high-efficiency porous thermoelectric materials through an unconventional melt-centrifugation technique.