DIFFUSION AND CORRELATION-EFFECTS IN IRON-DOPED COO

The diffusion of **5**9Fe and **6**0Co has been measured in pure CoO and dilute iron-doped CoO, (CO//1// minus //cFe//c)O, as a function of temperature (1000-1400 degree C) and oxygen partial pressure p(O//2) (10** minus **7 less than equivalent to p(O//2) less than equivalent to 0. 21 atm). The enhancement factors for the diffusivities of iron and cobalt are nearly identical, which suggests that the primary cause of the enhancement is the increased concentration of charge-compensating cation vacancies with the addition of iron. The Fe ions dissolved in CoO appear to exist as a mixture of Fe**2** plus and Fe**3** plus ions; the fraction of iron ions in the three-plus state decreases with decreasing p(O//2). The simultaneous diffusion of **5**2Fe and **5**9Fe has been measured as a function of p(O//2) at 1200 degree C.