Effects of Mechanical Milling with Ag Powder on Thermoelectric Properties of Na_xCo_2O_4 Polycrystal Synthesized through Citric Acid Complex Process

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概要

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• Na<SUB>x</SUB>Co<SUB>2</SUB>O<SUB>4</SUB> powders synthesized by citric acid complex (CAC) process were mechanically milled with Ag particles around 1μm in size and then pressurelessly sintered. Effects of the mechanical milling on microstructure and thermoelectric properties of a Na<SUB>x</SUB>Co<SUB>2</SUB>O<SUB>4</SUB>/Ag composite were investigated. Ag powder was finely dispersed in the Na<SUB>x</SUB>Co<SUB>2</SUB>O<SUB>4</SUB>/Ag mixed powder after mechanical milling. The Na<SUB>x</SUB>Co<SUB>2</SUB>O<SUB>4</SUB>/Ag sintered bodies showed the large crystallographic anisotropy as compared to the Na<SUB>x</SUB>Co<SUB>2</SUB>O<SUB>4</SUB>/Ag composite synthesized by the conventional CAC process. However, Ag particles were coarsened during sintering, and the Na<SUB>x</SUB>Co<SUB>2</SUB>O<SUB>4</SUB>/Ag composite polycrystal with dispersion of fine Ag grains could not be obtained. By Ag addition, the electrical resistivity was significantly reduced, but the thermal conductivity was increased because of the coarse Ag phase, resulting in the dimensionless figure of merit almost the same as, or smaller than, that of the sample without Ag.

• 社団法人粉体粉末冶金協会の論文
• 2008-02-15

著者

• Ito Mikio

  Course Of Materials Sci. And Engineering Div. Of Materials And Manufacturing Sci. Graduate School Of

• Ito Mikio

  Course Of Materials Science And Engineering Division Of Materials And Manufacturing Science Graduate

• Sumiyoshi Junji

  Osaka University

関連論文

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• Synthesis of Y-Doped n-Type SrTiO_3 Thermoelectric Oxides by Polymerized Complex Process
• Synthesis of Thermoelectric Fe_Co_Si_2 with Fine Ag Dispersion by Mechanical Milling with AgO Powder
• Effects of Ag Addition on Microstructure and Thermoelectric Properties of Na_xCo_2O_4 Synthesized by Citric Acid Complex Process
• Effects of Mechanical Milling with Ag Powder on Thermoelectric Properties of Na_xCo_2O_4 Polycrystal Synthesized through Citric Acid Complex Process

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