Effects of Mechanical Milling with Ag Powder on Thermoelectric Properties of NaxCo2O4 Polycrystal Synthesized through Citric Acid Complex Process

• Ito Mikio

  Course of Materials Science and Engineering, Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University

• Sumiyoshi Junji

  Osaka University

Abstract

Na_xCo₂O₄ 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_xCo₂O₄/Ag composite were investigated. Ag powder was finely dispersed in the Na_xCo₂O₄/Ag mixed powder after mechanical milling. The Na_xCo₂O₄/Ag sintered bodies showed the large crystallographic anisotropy as compared to the Na_xCo₂O₄/Ag composite synthesized by the conventional CAC process. However, Ag particles were coarsened during sintering, and the Na_xCo₂O₄/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.

Journal

• Journal of the Japan Society of Powder and Powder Metallurgy

  Journal of the Japan Society of Powder and Powder Metallurgy 55 (2), 90-95, 2007

  Japan Society of Powder and Powder Metallurgy

Keywords

• oxide/metal composite
• citric acid complex process
• mechanical milling
• crystallographic anisotropy
• thermoelectric properties

Details

• CRID: 1390282681284709248
• NII Article ID: 10021172632
• NII Book ID: AN00222724
• DOI: 10.2497/jjspm.55.90
• ISSN: 18809014
• ISSN: 05328799
• NDL BIB ID: 9390020
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I9390020
• Text Lang: en
• Data Source:
  • JaLC
  • NDL
  • Crossref
  • CiNii Articles
• Abstract License Flag: Disallowed