Self-Diffusion of Oxygen Ion in Lithium Oxide

Self－diffusion coefficients of the oxygen ion in antifluorite-cubic Li_2O were determined by means of the gas-solid isotope exchange and solid-phase analysis technique using ^<18>O as the tracer. The lattice diffusion coefficient was estimated by utilizing the relationship between grain-size and particl-size dependences of the apparent diffusion coefficients determined for polycrystalline samples. Diffusion characteristics of the constituent ions in antifluorite-cubic crystals were discussed in comparison with those in fluoritecubic crystals. The ionic conductivity for Li_2O was discussed in terms of the diffusivities of both constituent ions

Self-Diffusion of Oxygen in Molten Silicate Systems PbO-SiO_2 and CaO-SiO_2

The exchange ratio and the exchange rate of oxygen between the gas and liquid phases were measured in molten silicate systems PbO-SiO_2 and CaO-SiO_2 using ^<18>O as the tracer. It was clarified that not all of the oxygen in the system PbO-SiO_2 took part in the exchange. In contrast, in the system CaO-SiO_2 all of the oxygen contributed to the exchange. Self-diffusion coefficients of oxygen were determined using the exchange rates for the two systems. The results were compared with the self-diffusion coefficients of silicon for the respective systems. On the basis of the results, the self-diffusion mechanism of oxygen was discussed