| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1488425 | Materials Research Bulletin | 2014 | 5 Pages |
•We report direct synthesis of the high temperature stable phase, P3-Na0.6CoO2.•The hydrothermal synthesis of P3-Na0.6CoO2 involves one step and low temperature.•The yield diagram for Na–Co–H2O system has been builded up to 250 °C.•We propose a formation mechanism of P3-Na0.6CoO2 phase using the unit cell theory.•The thermal stability of P3-Na0.6CoO2 has been investigated by means of HT-XRD.
In order to obtain the layered sodium cobalt oxide materials by hydrothermal synthesis, the yield diagram for Na–Co–H2O system has been built and studied. In the same time, the well-known data of Co–H2O system have been extended at 250 °C in basic solution.We had first synthesized directly the high temperature stable phase, P3-Na0.6CoO2P3-Na0.6CoO2 by a one-step low-temperature hydrothermal method. The rhombohedral structure of P3-Na0.6CoO2P3-Na0.6CoO2 has been determined by X-ray diffraction (XRD) and the purity of phases has been confirmed by XPS. The thermal stability of P3-Na0.6CoO2P3-Na0.6CoO2 has been investigated by means of high temperature X-ray diffraction in 298–873 K range and when the temperature has reached 723 K, the completely transformation of P3-Na0.6CoO2P3-Na0.6CoO2 in the rhombohedral stable phase α-NaCoO2α-NaCoO2 (space group R-3m ) was observed. Also, a formation mechanism of P3-Na0.6CoO2P3-Na0.6CoO2 phase using the unit cell theory in the hydrothermal process was proposed.
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