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Superconductivity, charge ordering and structural properties of alpha and beta-NaxCoO2.y(H2O, D2O)

Y. G. Shi·H. X. Yang·H. Huang·X. Liu·J. Q. Li
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Abstract

Two series of alpha and beta-NaxCoO2 materials have been prepared by means of Na deintercalation from the parent alpha-NaCoO2 and beta-Na0.6CoO2 phases, respectively. The alpha-NaxCoO2 materials undergo a clear phase transition from the hexagonal to the beta-phase like monoclinic structure along with Na deintercalation. Measurements of resistivity and magnetization demonstrated the presence notable charge ordering transitions in both alpha and beta-NaxCoO2 with 0.4 < x < 0.5 below 100K. Bulk Superconductivity has been observed in the hydrated alpha-NaxCoO2.1.3H2O at ~4.5K and in beta-NaxCoO2.1.3H2O at \~4.3K. Intercalation of D2O in alpha and beta-Na0.33CoO2 also yields superconductivity at slightly lower temperatures. It is worthy to note that, despite of the structural difference, the alpha-, beta- and gamma-NaxCoO2 .yH2O materials show up notable commonalities in their essential physical properties, e.g. superconductivity and charge ordering transitions.

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Y. G. Shi, H. X. Yang, H. Huang, X. Liu, J. Q. Li. 2005-08-21. Superconductivity, charge ordering and structural properties of alpha and beta-NaxCoO2.y(H2O, D2O). https://doi.org/10.1103/physrevb.73.094505

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