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Tellurium-evaporation-annealing for p-type bismuth-antimony-telluride thermoelectric materials
- Tellurium-evaporation-annealing for p-type bismuth-antimony-telluride thermoelectric materials
- Kim, DH[Kim, Dong Hwan]; Kwon, IH[Kwon, In Hye]; Kim, C[Kim, Cham]; Han, B[Han, Byungchan]; Im, HJ[Im, Hee-Joong]; Kim, H[Kim, Hoyoung]
- DGIST Authors
- Kim, DH[Kim, Dong Hwan]; Kwon, IH[Kwon, In Hye]; Kim, C[Kim, Cham]; Han, B[Han, Byungchan]; Kim, H[Kim, Hoyoung]
- Issue Date
- Journal of Alloys and Compounds, 548, 126-132
- Article Type
- Ab Initio Density Functional Theories (DFT); Annealing; Annealing Methods; Anti-Site Defect; Antimony Compounds; Bismuth; Bismuth Antimony Telluride; Bismuth Compounds; Bulk Alloys; Calculations; Carrier Concentration; Chemical Compositions; Density Functional Theory; Evaporation; Experimental Measurements; Figure of Merits; Nano Scale; P-Type; Phase Transitions; Sintering; Tellurium; Tellurium Compounds; Thermo-Electric; Thermo-Electric Material; Thermo-Electric Performance; Thermo-Electricity; Underlying Mechanism
- A tellurium evaporation annealing method has been investigated to control the carrier concentration of sintered (Bi,Sb)2Te3 compounds. Hot-pressed (Bi,Sb)2Te3 bulk alloys and tellurium powders located in an evacuated ampoule, were heated to 673 K and held for 3, 12 and 48 h. The crystal structure and chemical composition in the annealed specimens were preserved, while the carrier concentrations were varied between 1.53 × 1019 and 2.57 × 1019 cm -3, and the thermal conductivity at 300 K ranged between 1.20 and 1.25 W m-1 K-1. The figure of merit at 300 K was enhanced from 0.86 to 1.06 when the specimens were annealed for 3 h. To identify the underlying mechanism, we utilized ab initio density functional theory calculations. These computations indicated that a Te ad-layer on top of the Bi2Te3 energetically favors bulk Bi atoms to migrate to the surface. Our experimental measurements and the first-principles validations consistently indicate that the tellurium evaporation annealing method is a novel process for enhancing the thermoelectric performance of Bi-Te compounds by controlling their carrier concentrations, which is particularly useful in dealing with nano-scale composites. © 2012 Elsevier B.V. All rights reserved.
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