Microstructures and thermoelectric properties of NaCo2O4 prepared by double-step sintering

Michitaka Ohtaki; Eishi Maeda

doi:10.2497/jjspm.47.1159

Microstructures and thermoelectric properties of NaCo₂O₄ prepared by double-step sintering

Michitaka Ohtaki, Eishi Maeda

Research output: Contribution to journal › Article › peer-review

26 Citations (Scopus)

Abstract

The thermoelectric properties of sintered bodies of NaCo₂O₄, which is so far the most promising p-type candidate for oxide thermoelectric material, are investigated in terms of their sintering conditions. Double-step sintering, for which single-phase NaCo₂O₄ obtained by calcination and sintering with addition of 10% excess of Na each time is re-ground and sintered again, is revealed to attain a marked improvement in the thermoelectric performance of the oxide. The improvement is due to increase in both Seebeck coefficient and electrical conductivity, and is attributed to a distinct enhancement of the two-dimensionality in the crystallites constituting the sintered body. The oxide sintered body consequently attains the figure-of-merit of 0.88×10^-3 K^-1 at 600 °C, and the maximum ZT of 0.78 at 800 °C.

Original language	English
Pages (from-to)	1159-1164
Number of pages	6
Journal	Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy
Volume	47
Issue number	11
DOIs	https://doi.org/10.2497/jjspm.47.1159
Publication status	Published - Nov 2000

All Science Journal Classification (ASJC) codes

Mechanical Engineering
Industrial and Manufacturing Engineering
Metals and Alloys
Materials Chemistry

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abstract = "The thermoelectric properties of sintered bodies of NaCo2O4, which is so far the most promising p-type candidate for oxide thermoelectric material, are investigated in terms of their sintering conditions. Double-step sintering, for which single-phase NaCo2O4 obtained by calcination and sintering with addition of 10% excess of Na each time is re-ground and sintered again, is revealed to attain a marked improvement in the thermoelectric performance of the oxide. The improvement is due to increase in both Seebeck coefficient and electrical conductivity, and is attributed to a distinct enhancement of the two-dimensionality in the crystallites constituting the sintered body. The oxide sintered body consequently attains the figure-of-merit of 0.88×10-3 K-1 at 600 °C, and the maximum ZT of 0.78 at 800 °C.",

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AU - Maeda, Eishi

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Microstructures and thermoelectric properties of NaCo₂O₄ prepared by double-step sintering

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