Thermoelectric transport enhancement of Te-rich bismuth antimony telluride(Bi_(0.5)Sb_(1.5)Te_(3+x))through controlled porosity  

作　　者：Ian T.Witting Jann A.Grovogui Vinayak P.Dravid G.Jeffrey Snyder 

机构地区：[1]Department of Materials Science and Engineering,Northwestern University,2220 Campus Drive,Cook Hall 2036,Evanston,IL,60208,USA

出　　处：《Journal of Materiomics》2020年第3期532-544,共13页无机材料学学报（英文）

基　　金：supported by the U.S.Department of Energy,Office of Science and Office of Basic Energy Sciences under award number DE-SC0014520;the EPIC facility of Northwestern University’s NUANCE Center,support from the Soft and Hybrid Nanotechnology Experimental(SHyNE)Resource(NSF ECCS-1542205);the MRSEC Program(NSF DMR-1720139)at the Materials Research Center;the International Institute for Nanotechnology(IIN);the Keck Foundation;the State of Illinois,through the IIN;the MatCI Facility which receives support from the MRSEC Program(NSF DMR-1720139)of the Materials Research Center at Northwestern University;supported by the National Science Foundation Graduate Research Fellowship under Grant No.DGE-1324585.

摘　　要：Alloys of Bi_(2)Te_(3) and Sb_(2)Te_(3) 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 Bi_(0.5)Sb_(1.5)Te_(3+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.

关 键 词：Bismuth antimony telluride Thermoelectric POROSITY Transport modeling FOAMING 

分 类 号：TB34[一般工业技术—材料科学与工程]