Structure of ionic and electronic defects in cobalt bronze NaxCoO2

Thermogravimetric and electrical conductivity measurements of cobalt bronze Na_0.7CoO₂ have been carried out in the temperature range 990-670 K and over oxygen pressures from 100 to 10 kPa. It has been stated that in addition to defects in the sodium sublattice (sodium vacancies and electron holes) in this material there are also ionic defects in the oxygen-cobalt sublattice. The proposed method of analysis of defect type, based on the calculation of derivative of the function ln (def) = f(lnP_O2) shows the existence of cobalt ions Co³⁺ in the sodium sites.