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Title: Phase Selectivity and Stability in Compositionally Complex Nano (nA1/n)Co2O4
Award ID(s):
2145174
PAR ID:
10497898
Author(s) / Creator(s):
; ; ; ; ;
Publisher / Repository:
American Chemical Society
Date Published:
Journal Name:
Chemistry of Materials
Volume:
35
Issue:
17
ISSN:
0897-4756
Page Range / eLocation ID:
7283 to 7291
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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  1. Abstract

    The Ag and In co‐doped PbTe, AgnPb100InnTe100+2n(LIST), exhibitsn‐type behavior and features unique inherent electronic levels that induce self‐tuning carrier density. Results show that In is amphoteric in the LIST, forming both In3+and In1+centers. Through unique interplay of valence fluctuations in the In centers and conduction band filling, the electron carrier density can be increased from ≈3.1 × 1018cm−3at 323 K to ≈2.4 × 1019cm−3at 820 K, leading to large power factors peaking at ≈16.0 µWcm−1K−2at 873 K. The lone pair of electrons from In+can be thermally continuously promoted into the conduction band forming In3+, consistent with the amphoteric character of In. Moreover, with rising temperature, the Fermi level shifts into the conduction band, which enlarges the optical band gap based on the Moss–Burstein effect, and reduces bipolar diffusion and thermal conductivity. Adding extra Ag in LIST improves the electrical transport properties and meanwhile lowers the lattice thermal conductivity to ≈0.40 Wm−1K−1. The addition of Ag creates spindle‐shaped Ag2Te nanoprecipitates and atomic‐scale interstitials that scatter a broader set of phonons. As a result, a maximumZTvalue ≈1.5 at 873 K is achieved in Ag6Pb100InTe102(LIST).

     
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