Electrochemical De-intercalation, Oxygen Non-stoichiometry, and Crystal Growth of NaxCoO2-d

Abstract

We report a detailed study of de-intercalation of Na from the compound NaxCoO2-d using an electrochemical technique. We find evidence for stable phases with Na contents near the fractions ~1/3, 1/2, 5/8, 2/3, and 3/4. Details regarding the floating-zone crystal growth of Na0.75CoO2 single crystals are discussed as well as results from magnetic susceptibility measurements. We observe the presence of significant oxygen deficiencies in powder samples of Na0.75CoO2-d prepared in air, but not in single crystal samples prepared in an oxygen atmosphere. The oxygen deficiencies in a Na0.75CoO2-d sample with d ~ 0.08 remain even after electrochemically de-intercalating to Na0.3CoO2-d.

6 pages, 5 figures

References in corpus (2)

• Bulk antiferromagnetism in $\mathbf{N}{\mathbf{a}}_{0.82}\mathbf{Co}{\mathbf{O}}_2$ single crystals
• Observation of Bulk Superconductivity in NaxCoO2.yH2O and NaxCoO2.yD2O Powder and Single Crystals

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