OXYGEN DIFFUSION IN PEROVSKITE - IMPLICATIONS FOR ELECTRICAL-CONDUCTIVITY IN THE LOWER MANTLE

Experimental determination of oxygen self-diffusion in CaTiO3 perovskite, a structural analog of (Mg,Fe)SiO3 perovskite, confirms a theoretical relation between diffusion constants and anion porosity. Oxygen diffusion rates in (Mg,Fe)SiO3 perovskite calculated with this relation increase by about eight orders of magnitude through the lower mantle. Electrical conductivity values calculated from these diffusion rates are consistent with inferred conductivity values for the lower mantle. This result suggests that the dominant conductivity mechanism in the deep mantle is ionic.