Zhang X, Zhang Y, Wu L, Tsuruta A, Mikami M, Cho HJ, Ohta H. Ba
1/3CoO
2: A Thermoelectric Oxide Showing a Reliable
ZT of ∼0.55 at 600 °C in Air.
ACS Appl Mater Interfaces 2022;
14:33355-33360. [PMID:
35819907 PMCID:
PMC9335523 DOI:
10.1021/acsami.2c08555]
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Abstract
Thermoelectric energy conversion technology has attracted attention as an energy harvesting technology that converts waste heat into electricity by means of the Seebeck effect. Oxide-based thermoelectric materials that show a high figure of merit are promising because of their good chemical and thermal stability as well as their harmless nature compared to chalcogenide-based state-of-the-art thermoelectric materials. Although several high-ZT thermoelectric oxides (ZT > 1) have been reported thus far, the reliability is low due to a lack of careful observation of their stability at elevated temperatures. Here, we show a reliable high-ZT thermoelectric oxide, Ba1/3CoO2. We fabricated Ba1/3CoO2 epitaxial films by the reactive solid-phase epitaxy method (Na3/4CoO2) followed by ion exchange (Na+ → Ba2+) treatment and performed thermal annealing of the film at high temperatures and structural and electrical measurements. The crystal structure and electrical resistivity of the Ba1/3CoO2 epitaxial films were found to be maintained up to 600 °C. The power factor gradually increased to ∼1.2 mW m-1 K-2 and the thermal conductivity gradually decreased to ∼1.9 W m-1 K-1 with increasing temperature up to 600 °C. Consequently, the ZT reached ∼0.55 at 600 °C in air.
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