Electrical conductivity of SiO<sub>2</sub> at extreme conditions and planetary dynamos.

Scipioni, Roberto; Stixrude, Lars; Desjarlais, Michael P · Proc Natl Acad Sci U S A · 2017

basic_science · Level V

Where this comes from

Abstract

Ab intio molecular dynamics simulations show that the electrical conductivity of liquid SiO<sub>2</sub> is semimetallic at the conditions of the deep molten mantle of early Earth and super-Earths, raising the possibility of silicate dynamos in these bodies. Whereas the electrical conductivity increases uniformly with increasing temperature, it depends nonmonotonically on compression. At very high pressure, the electrical conductivity decreases on compression, opposite to the behavior of many materials. We show that this behavior is caused by a novel compression mechanism: the development of broken charge ordering, and its influence on the electronic band gap.