Sintering process and nonstoichiometry of NaCo2O4 layered thermoelectric oxide

M. Ohtaki; K. Shouji

doi:10.1109/ICT.2003.1287490

Sintering process and nonstoichiometry of NaCo₂O₄ layered thermoelectric oxide

M. Ohtaki, K. Shouji

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

3 Citations (Scopus)

Abstract

Sintering process of layered oxide NaCo₂O₄, which has been the best p-type thermoelectric oxide candidate to date since its debut in the world of thermoelectrics in 1997, was investigated in terms of sodium nonstoichiometry occurring during solid state reaction between Na₂CO₃ and Co₃O₄ for the synthesis of the oxide. Thermal gravimetry (TG) and differential thermal analysis (DTA) measurements revealed that solid-gas equilibrium plays an important role on phase formation process and on controlling chemical composition of the oxide, Partial pressure of oxygen and carbon dioxide in the reaction atmosphere was revealed to be crucial for controlling vaporization of Na, as well as for promotion of phase formation reaction of NaCo₂O₄, In particular, whereas the CO₂ atmosphere effectively suppressed abrupt dissociation reaction of Na₂CO₃, low oxygen partial pressure accelerated vaporization of Na at lower temperature. Interestingly, high partial pressure Of CO₂ appeared to hinder phase formation reaction of NaCo₂O₄ even at the same oxygen partial pressure as that under the aerobic conditions.

Original language	English
Title of host publication	Proceedings ICT 2003 - 22nd International Conference on Thermoelectrics
Publisher	Institute of Electrical and Electronics Engineers Inc.
Pages	227-230
Number of pages	4
ISBN (Electronic)	078038301X
DOIs	https://doi.org/10.1109/ICT.2003.1287490
Publication status	Published - 2003
Event	22nd International Conference on Thermoelectrics, ICT 2003 - La Grande Motte, France Duration: Aug 17 2003 → Aug 21 2003

Publication series

Name	International Conference on Thermoelectrics, ICT, Proceedings
Volume	2003-January

Other

Other	22nd International Conference on Thermoelectrics, ICT 2003
Country/Territory	France
City	La Grande Motte
Period	8/17/03 → 8/21/03

All Science Journal Classification (ASJC) codes

Condensed Matter Physics
Electrical and Electronic Engineering

Access to Document

10.1109/ICT.2003.1287490

Cite this

Ohtaki, M., & Shouji, K. (2003). Sintering process and nonstoichiometry of NaCo₂O₄ layered thermoelectric oxide. In Proceedings ICT 2003 - 22nd International Conference on Thermoelectrics (pp. 227-230). [1287490] (International Conference on Thermoelectrics, ICT, Proceedings; Vol. 2003-January). Institute of Electrical and Electronics Engineers Inc.. https://doi.org/10.1109/ICT.2003.1287490

Sintering process and nonstoichiometry of NaCo₂O₄ layered thermoelectric oxide. / Ohtaki, M.; Shouji, K.

Proceedings ICT 2003 - 22nd International Conference on Thermoelectrics. Institute of Electrical and Electronics Engineers Inc., 2003. p. 227-230 1287490 (International Conference on Thermoelectrics, ICT, Proceedings; Vol. 2003-January).

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

Ohtaki, M & Shouji, K 2003, Sintering process and nonstoichiometry of NaCo₂O₄ layered thermoelectric oxide. in Proceedings ICT 2003 - 22nd International Conference on Thermoelectrics., 1287490, International Conference on Thermoelectrics, ICT, Proceedings, vol. 2003-January, Institute of Electrical and Electronics Engineers Inc., pp. 227-230, 22nd International Conference on Thermoelectrics, ICT 2003, La Grande Motte, France, 8/17/03. https://doi.org/10.1109/ICT.2003.1287490

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title = "Sintering process and nonstoichiometry of NaCo2O4 layered thermoelectric oxide",

abstract = "Sintering process of layered oxide NaCo2O4, which has been the best p-type thermoelectric oxide candidate to date since its debut in the world of thermoelectrics in 1997, was investigated in terms of sodium nonstoichiometry occurring during solid state reaction between Na2CO3 and Co3O4 for the synthesis of the oxide. Thermal gravimetry (TG) and differential thermal analysis (DTA) measurements revealed that solid-gas equilibrium plays an important role on phase formation process and on controlling chemical composition of the oxide, Partial pressure of oxygen and carbon dioxide in the reaction atmosphere was revealed to be crucial for controlling vaporization of Na, as well as for promotion of phase formation reaction of NaCo2O4, In particular, whereas the CO2 atmosphere effectively suppressed abrupt dissociation reaction of Na2CO3, low oxygen partial pressure accelerated vaporization of Na at lower temperature. Interestingly, high partial pressure Of CO2 appeared to hinder phase formation reaction of NaCo2O4 even at the same oxygen partial pressure as that under the aerobic conditions.",

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