Structural properties and superconductivity of Na0.3CoO2·1.3H2O superconductors

The synthesis, superconductivity and structural properties of Na0.3CoO2·1.3H2O superconductors have been investigated. Analysis demonstrates that the basic crystal structure of this superconducting phase has a hexagonal cell with the P6 3/mmc space group symmetry. Electron microscopy observations reveal a prominent layer feature along the c－direction and a new superstructure within the CoO2 layers. Electron energy loss spectrometry analyses show that the Co ions have valence states of around +3.7 in this superconducting materials.