The Effect of Alumina on the Electrical Conductivity of Silicate Perovskite

Abstract

Measurements of the electrical conductivity of silicate perovskite at 25 gigapascals and 1400° to 1600°C show that the conductivity of (Mg,Fe)SiO 3 perovskite containing 2.89 weight percent Al 2 O 3 is about 3.5 times greater than that of aluminum-free (Mg 0.915 Fe 0.085 )SiO 3 perovskite. The conduction mechanism in perovskite between 1400° and 1600°C is most likely by polarons, because Mössbauer studies show that the aluminum-bearing perovskite has about 3.5 times the amount of Fe 3+ as the aluminum-free sample. A conductivity-depth profile from 660 to 2900 kilometers based on aluminum-bearing perovskite is consistent with geophysical models.