Thermoelectric transport enhancement of Te-rich bismuth antimony telluride (Bi0.5Sb1.5Te3+x) through controlled porosity
Alloys of Bi2Te3 and Sb2Te3 are the best performing p-type thermoelectrics near room temperature and have been the subject of extensive engineering efforts. Dramatic improvement is achieved by introducing defects that effectively scatter phonons and reduce thermal conductivity. Unfortunately, outsta...
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doaj-29096c0f1bac4dc9bc0ad214ca5891be2020-11-25T03:18:53ZengElsevierJournal of Materiomics2352-84782020-09-0163532544Thermoelectric transport enhancement of Te-rich bismuth antimony telluride (Bi0.5Sb1.5Te3+x) through controlled porosityIan T. Witting0Jann A. Grovogui1Vinayak P. Dravid2G. Jeffrey Snyder3Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Cook Hall 2036, Evanston, IL, 60208, USADepartment of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Cook Hall 2036, Evanston, IL, 60208, USACorresponding author.; Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Cook Hall 2036, Evanston, IL, 60208, USACorresponding author.; Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Cook Hall 2036, Evanston, IL, 60208, USAAlloys of Bi2Te3 and Sb2Te3 are the best performing p-type thermoelectrics near room temperature and have been the subject of extensive engineering efforts. Dramatic improvement is achieved by introducing defects that effectively scatter phonons and reduce thermal conductivity. Unfortunately, outstanding results are often difficult to reproduce as the process variables involved are difficult to control or possibly unknown. Here, a reproducible and controllable method of fabricating porous Bi0.5Sb1.5Te3+x is presented. While effective medium theory (EMT) predicts no benefit, improvements in the thermoelectric quality factor, B (which determines the maximum zT of a materials), were as high as 45% parallel to the pressing direction for a sample of roughly 20% porosity. The study of microstructural evolution with increasing porosity is facilitated by a combination of Scanning/Transmission Electron Microscopy (S/TEM) and Electron Backscattered Diffraction (EBSD). This study reveals a statistically significant shift in the distribution of grain boundaries favoring lower energy twins, which coincides with an increase in the presence of stepped twin boundaries. This work demonstrates the potential benefits of careful grain boundary engineering and the need for further detailed studies of the dependence of thermal and electrical transport on grain boundary structure and orientation in these alloys.http://www.sciencedirect.com/science/article/pii/S2352847820300344Bismuth antimony tellurideThermoelectricPorosityTransport modelingFoaming |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Ian T. Witting Jann A. Grovogui Vinayak P. Dravid G. Jeffrey Snyder |
spellingShingle |
Ian T. Witting Jann A. Grovogui Vinayak P. Dravid G. Jeffrey Snyder Thermoelectric transport enhancement of Te-rich bismuth antimony telluride (Bi0.5Sb1.5Te3+x) through controlled porosity Journal of Materiomics Bismuth antimony telluride Thermoelectric Porosity Transport modeling Foaming |
author_facet |
Ian T. Witting Jann A. Grovogui Vinayak P. Dravid G. Jeffrey Snyder |
author_sort |
Ian T. Witting |
title |
Thermoelectric transport enhancement of Te-rich bismuth antimony telluride (Bi0.5Sb1.5Te3+x) through controlled porosity |
title_short |
Thermoelectric transport enhancement of Te-rich bismuth antimony telluride (Bi0.5Sb1.5Te3+x) through controlled porosity |
title_full |
Thermoelectric transport enhancement of Te-rich bismuth antimony telluride (Bi0.5Sb1.5Te3+x) through controlled porosity |
title_fullStr |
Thermoelectric transport enhancement of Te-rich bismuth antimony telluride (Bi0.5Sb1.5Te3+x) through controlled porosity |
title_full_unstemmed |
Thermoelectric transport enhancement of Te-rich bismuth antimony telluride (Bi0.5Sb1.5Te3+x) through controlled porosity |
title_sort |
thermoelectric transport enhancement of te-rich bismuth antimony telluride (bi0.5sb1.5te3+x) through controlled porosity |
publisher |
Elsevier |
series |
Journal of Materiomics |
issn |
2352-8478 |
publishDate |
2020-09-01 |
description |
Alloys of Bi2Te3 and Sb2Te3 are the best performing p-type thermoelectrics near room temperature and have been the subject of extensive engineering efforts. Dramatic improvement is achieved by introducing defects that effectively scatter phonons and reduce thermal conductivity. Unfortunately, outstanding results are often difficult to reproduce as the process variables involved are difficult to control or possibly unknown. Here, a reproducible and controllable method of fabricating porous Bi0.5Sb1.5Te3+x is presented. While effective medium theory (EMT) predicts no benefit, improvements in the thermoelectric quality factor, B (which determines the maximum zT of a materials), were as high as 45% parallel to the pressing direction for a sample of roughly 20% porosity. The study of microstructural evolution with increasing porosity is facilitated by a combination of Scanning/Transmission Electron Microscopy (S/TEM) and Electron Backscattered Diffraction (EBSD). This study reveals a statistically significant shift in the distribution of grain boundaries favoring lower energy twins, which coincides with an increase in the presence of stepped twin boundaries. This work demonstrates the potential benefits of careful grain boundary engineering and the need for further detailed studies of the dependence of thermal and electrical transport on grain boundary structure and orientation in these alloys. |
topic |
Bismuth antimony telluride Thermoelectric Porosity Transport modeling Foaming |
url |
http://www.sciencedirect.com/science/article/pii/S2352847820300344 |
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