Geophysics

Dropping ferric iron into a low spin

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Science  30 Nov 2018:
Vol. 362, Issue 6418, pp. 1015-1016
DOI: 10.1126/science.362.6418.1015-g

Iron located in lower-mantle bridgmanites undergoes a spin transition that could alter the seismic properties deep in Earth. Liu et al. found that ferric iron undergoes a spin transition in one of the cation sites of mantle bridgmanite at mid-mantle pressures. The completion of this now-well-constrained spin-transition pressure range roughly lines up with the point at which the relative viscosity of the lower mantle decreases while not having much impact on the seismic wave properties. These new data help us understand the dynamics and interpret the seismic picture of Earth's inaccessible mantle.

Nat. Comm. 9, 1284 (2018).

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