期刊
JOURNAL OF MATERIALS CHEMISTRY A
卷 6, 期 9, 页码 4079-4087出版社
ROYAL SOC CHEMISTRY
DOI: 10.1039/c7ta10859a
关键词
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资金
- Danish National research Foundation (Center for Materials Crystallography) [DNRF93]
- Innovation Foundation of Denmark (Center for Thermoelectric Energy Conversion)
- Danish Center for Synchrotron and Neutron Research (Danscatt)
- Research Council of Norway under Toppforsk program [250403]
Here we report that the thermoelectric properties of bulk -Zn4Sb3 can be improved in the range 300-575 K by Ag doping at the Zn sites. Proper Ag doping leads to decreased electrical resistivity and increased Seebeck coefficient, thus resulting in a large improvement in power factor. The figure of merit, zT, has an obvious enhancement due to Ag doping although the thermal conductivity is slightly increased. (Zn0.9925Ag0.0075)(4)Sb-3 exhibits a promising zT of approximate to 1.2 at 575 K, which is superior to most previously reported p-type doped Zn4Sb3 materials. Furthermore, the high-temperature thermal stability is studied in detail. The (Zn0.9925Ag0.0075)(4)Sb-3 bulk sample does not decompose even when the temperature is elevated to 793 K in vacuum. When the bulk sample is heated to 573 K in air, (Zn0.9925Ag0.0075)(4)Sb-3 is also stable, unlike undoped Zn4Sb3 where Zn whiskers come out of the surface. In-house in situ powder X-ray diffraction (PXRD) and multi-temperature synchrotron PXRD (up to 793 K) reveal that the undoped Zn4Sb3 powder sample starts decomposing into ZnSb at 473 K if exposed to the air and it is fully decomposed into ZnSb, ZnO, and Sb after cooling down from 793 to 300 K. However, there is approximate to 24 wt% Zn4Sb3 preserved in the (Zn0.995Ag0.005)(4)Sb-3 powder sample after the same heat treatment, while only approximate to 6 wt% Zn4Sb3 remains in (Zn0.99Ag0.01)(4)Sb-3. The above result indicates that proper Ag doping leads to enhanced high-temperature thermal stability in -Zn4Sb3. This work thereby suggests Ag-doped Zn4Sb3 bulk material as a promising candidate for thermoelectric applications in terms of enhanced performance as well as improved high-temperature thermal stability.
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