Precise control of Na content in the layered cobaltate γ-Na xCoO 2

Dai Igarashi, Yuzuru Miyazaki, Kunio Yubuta, Tsuyoshi Kajitani

研究成果: Contribution to journalArticle査読

7 被引用数 (Scopus)


We have developed a preparation method for precisely controlling the Na content x of a γ-Na 0.7CoO 2 precursor by a halogen oxidation technique in the range 0.50 ≤ x ≤ 0.70. The Na content of the precursor was reduced in a concentration-controlled I 2-CH 3CN solution. The magnetic susceptibility of γ-Na x CoO 2 shows Curie-Weiss (CW)-type paramagnetism (x ≈ 0.70) or Pauli-type paramagnetism (x ≈ 0.50). The boundary of the CW and Pauli paramagnetic phases was identified at x ≈ 0.61. The content and temperature for a disorder-order transition from the γ phase to a √7a 0 × √7a 0 superstructure were accurately elucidated by differential scanning calorimetry (DSC) measurement. A phase transition for the 0.52 ≤ x ≤ 0.54 sample was observed at 250 K by DSC measurements. The heat absorption of the 0.52 ≤ x ≤ 0.54 samples was of the same order of magnitude as that of the transition from the γ phase to the √7a 0 × √7a 0 phase.

ジャーナルJournal of Electronic Materials
出版ステータス出版済み - 9 2010

All Science Journal Classification (ASJC) codes

  • 電子材料、光学材料、および磁性材料
  • 凝縮系物理学
  • 電子工学および電気工学
  • 材料化学


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