Exploring Tantalum as a Potential Dopant to Promote the Thermoelectric Performance of Zinc Oxide
authors Arias-Serrano, BI; Xie, WJ; Aguirre, MH; Tobaldi, DM; Sarabando, AR; Rasekh, S; Mikhalev, SM; Frade, JR; Weidenkaff, A; Kovalevsky, AV
nationality International
author keywords zinc oxide; thermoelectrics; thermoelectric properties; donor doping; n-type semiconductor
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.
publisher MDPI
isbn 1996-1944
year published 2019
volume 12
issue 13
digital object identifier (doi) 10.3390/ma12132057
web of science category Materials Science, Multidisciplinary
subject category Materials Science
unique article identifier WOS:000477043900021
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