Low temperature synthesis of layered Na_xCoO_2 and K_XCoO_2 from NaOH/KOH fluxes and their ion exchange properties

摘要

We report a low temperature synthesis of layered Na_0-20CoO_2 and K_0.44CoO_2 phases from NaOH and KOH fluxes at 400 deg C.These layered oxides are employed to prepare hexagonal HCoO_2,Li_xCoO_2 and Delafossite AgCoO_2 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_0.02CoO_2 oxide exhibits isulating to metal like behaviour,whereas AaCoO_2 is semiconducting.