Low temperature synthesis of layered NaxCoO2 and KxCoO2 from NaOH/KOH fluxes and their ion exchange properties

We report a low temperature synthesis of layered Na_0.20Co0₂ and K_0.44CoO₂ phases from NaOH and KOH fluxes at 400°C. These layered oxides are employed to prepare hexagonal HCoO₂, Li_xCoO₂and Delafossite AgCoO₂ phases by ion exchange method. The resulting oxides were characterised by powder X-ray diffraction, X-ray photoelectron spectroscopy, SEM and EDX analysis. Final compositions of all these oxides are obtained from chemical analysis of elements present. Na_0.20Co0₂ oxide exhibits insulating to metal like behaviour, whereas AgCoO₂ is semiconducting. Dedicated to Professor C N R Rao on his 70th birthday