High Thermoelectric Figure of Merit Achieved in Cu 2 S 1- x Te x Alloys Synthesized by Mechanical Alloying and Spark Plasma Sintering
Chalcogenides have been considered as promising thermoelectric materials because of their low cost, nontoxicity, and environmental benignity. In this work, we synthesized a series of Cu S Te (0 ≤ x ≤ 1) alloys by a facile, rapid method of mechanical alloying combined with spark plasma sintering proc...
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Published in | ACS applied materials & interfaces Vol. 10; no. 38; pp. 32201 - 32211 |
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Main Authors | , , , , , , , |
Format | Journal Article |
Language | English |
Published |
United States
26.09.2018
|
Subjects | |
Online Access | Get full text |
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Summary: | Chalcogenides have been considered as promising thermoelectric materials because of their low cost, nontoxicity, and environmental benignity. In this work, we synthesized a series of Cu
S
Te
(0 ≤ x ≤ 1) alloys by a facile, rapid method of mechanical alloying combined with spark plasma sintering process. The Cu
S
Te
system provides an excellent vision of the competition between pure phase and phase transformation, entropy-driven solid solution, and enthalpy-driven phase separation. When the Te concentration increases, the Cu
S
Te
system changed from the pure monoclinic Cu
S at x = 0 to monoclinic Cu
S
Te
solid solution at 0.02 ≤ x ≤ 0.06 and then transforms to hexagonal Cu
S
Te
solid solution at 0.08 ≤ x ≤ 0.1. The phase separation of hexagonal Cu
Te in the hexagonal Cu
S matrix occurs at 0.3 ≤ x ≤ 0.7 and finally forms the hexagonal Cu
Te at x = 1. Owing to the changed band structure and the coexisted Cu
S and Cu
Te phases, greatly enhanced power factor was achieved in all Cu
S
Te
(0 < x < 1) alloys. Meanwhile, the point defect introduced by the substitution of Te/S atoms strengthened the phonon scattering, resulting in a lowered lattice thermal conductivity in most of these solid solutions. As a consequence, Cu
S
Te
exhibits a maximum ZT value of 1.18 at 723 K, which is about 3.7 and 14.8 times as compared to the values of pristine Cu
S (0.32) and Cu
Te (0.08), respectively. |
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ISSN: | 1944-8244 1944-8252 |
DOI: | 10.1021/acsami.8b11300 |