A high-temperature electrical conduction mechanism in the lower mantle phase (Mg,Fe),O1-x

Measurements of electrical conductivity at high pressure and temperature were taken on the lower mantle phase magnesiowustite with varying Fe3+ content. Although previous measurements at atmospheric pressure suggest Fe2+-Fe3+ hopping (small polaron) as the dominant conductivity mechanism, the present experiments show a change in charge transport mechanism with temperature. The lower temperature measurements are consistent with small polaron conduction, but at higher temperatures, which are more applicable to the lower mantle, a large polaron mechanism is suggested, Because these mechanisms have different temperature and compositional dependencies, this transition has important implications for extrapolation to mantle conditions.