OXYGEN SELF-DIFFUSION IN UNDOPED AND DOPED COBALTOUS OXIDE

The diffusion coefficient of O-18 in CoO has been measured in the temperature range from 1175° to 1560°C. Diffusion was measured in undoped CoO crystals and in crystals containing from 0.1 to 0.5 molar percent of aluminum or lithium. The diffusion coefficient in the undoped crystals is represented by the expression, D = 50 exp[-(95,000±5000)]/RT cm2 sec, at P02 = 0.21 atm. At a constant temperature and a constant oxygen partial pressure, the diffusion coefficient in doped crystals was found to increase or decrease with increasing concentration of lithium or aluminum in the oxide crystals. The results are discussed in terms of oxygen diffusion by a vacancy mechanism. © 1969.