Fig. 5
From: Valence and spin states of iron are invisible in Earth’s lower mantle
The electrical conductivity of three bridgmanite compositions across the spin transition at high pressures and 300 K. The red open triangles and blue asterisks are for (Mg0.46Fe3+0.53)(Si0.49Fe3+0.51)O3 Bdg along two successive compression paths by using the same DAC. The uncertainty is smaller than the symbol size. The yellow region marks the pressure range (43–53 GPa) of the spin transition in the B-site Fe3+, in this study constrained by complementary XRD and XES measurements. The dashed line is a linear fit to the electrical conductivity data up to 40 GPa, which predicts slightly higher conductivity than measured data above 54 GPa. Between 40 and 54 GPa, there is a 0.18–0.29 log unit drop in electrical conductivity as a result of spin transition in the B-site Fe3+. In comparison, Ohta et al. 45 reported a more significant drop (~0.5 log unit) between 70 and 85 GPa in (Mg0.9Fe0.1)SiO3 Bdg (black open circles). In contrast to ref.45, ref.46 reported much smoother conductivity profile for Mg0.828Fe0.208Al0.059Si0.911O3 Bdg. Note that the conductivity trend from ref.46 also exhibits a dip within the spin transition pressure range from this study
