Physics – Condensed Matter – Materials Science
Scientific paper
2004-07-23
Physics
Condensed Matter
Materials Science
4 pages (2 figures included) and 2 extra figures (gif), to be published in J. Phys. Soc. Jpn. 73 (8) with possible minor revis
Scientific paper
10.1143/JPSJ.73.2081
Powder Na$_{x}$CoO$_{2}$ ($0.70\leq x\leq 0.84$) samples were synthesized and characterized carefully by X-ray diffraction analysis, inductive-coupled plasma atomic emission spectroscopy, and redox titration. It was proved that $\gamma$-Na$_{x}$CoO$_{2}$ is formed only in the narrow range of $0.70\leq x\leq 0.78$. Nevertheless, the magnetic properties depend strongly on $x$. We found, for the first time, two characteristic features in the magnetic susceptibility of Na$_{0.78}$CoO$_{2}$, a sharp peak at $T_{p}=16$ K and an anomaly at $T_{k}=9$ K, as well as the transition at $T_{c}=22$ K and the broad maximum at $T_{m}=50$ K which had already been reported. A type of weak ferromagnetic transition seems to occur at $T_{k}$. The transition at $T_{c}$, which is believed to be caused by spin density wave formation, was observed clearly for $x\geq 0.74$ with constant $T_{c}$ and $T_{p}$ independent of $x$. On the other hand, ferromagnetic moment varies systematically depending on $x$. These facts suggest the occurrence of a phase separation at the microscopic level, such as the separation into Na-rich and Na-poor domains due to the segregation of Na ions. The magnetic phase diagram and transition mechanism proposed previously should be reconsidered.
Sakurai Haruo
Takayama-Muromachi Eiji
Takenouchi S.
Tsujii Naoto
No associations
LandOfFree
Synthesis, Characterization, and Magnetic Properties of gamma-NaxCoO2 (0.70 < x <0.84) does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Synthesis, Characterization, and Magnetic Properties of gamma-NaxCoO2 (0.70 < x <0.84), we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Synthesis, Characterization, and Magnetic Properties of gamma-NaxCoO2 (0.70 < x <0.84) will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-246017