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authors |
Arias-Serrano, BI; Xie, WJ; Aguirre, MH; Tobaldi, DM; Sarabando, AR; Rasekh, S; Mikhalev, SM; Frade, JR; Weidenkaff, A; Kovalevsky, AV |
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nationality |
International |
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journal |
MATERIALS |
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author keywords |
zinc oxide; thermoelectrics; thermoelectric properties; donor doping; n-type semiconductor |
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keywords |
DOPED ZNO NANOPARTICLES; OPTICAL-PROPERTIES; CONDUCTIVITY; CERAMICS |
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abstract |
Zinc oxide (ZnO) has being recognised as a potentially interesting thermoelectric material, allowing flexible tuning of the electrical properties by donor doping. This work focuses on the assessment of tantalum doping effects on the relevant structural, microstructural, optical and thermoelectric properties of ZnO. Processing of the samples with a nominal composition Zn1-xTaxO by conventional solid-state route results in limited solubility of Ta in the wurtzite structure. Electronic doping is accompanied by the formation of other defects and dislocations as a compensation mechanism and simultaneous segregation of ZnTa2O6 at the grain boundaries. Highly defective structure and partial blocking of the grain boundaries suppress the electrical transport, while the evolution of Seebeck coefficient and band gap suggest that the charge carrier concentration continuously increases from x = 0 to 0.008. Thermal conductivity is almost not affected by the tantalum content. The highest ZT0.07 at 1175 K observed for Zn0.998Ta0.002O is mainly provided by high Seebeck coefficient (-464 mu V/K) along with a moderate electrical conductivity of 13 S/cm. The results suggest that tantalum may represent a suitable dopant for thermoelectric zinc oxide, but this requires the application of specific processing methods and compositional design to enhance the solubility of Ta in wurtzite lattice. |
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publisher |
MDPI |
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isbn |
1996-1944 |
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year published |
2019 |
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volume |
12 |
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issue |
13 |
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digital object identifier (doi) |
10.3390/ma12132057 |
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web of science category |
Materials Science, Multidisciplinary |
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subject category |
Materials Science |
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unique article identifier |
WOS:000477043900021
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