RheoMan: a five-year, ERC-funded (Advanced Grant), project to model the rheology of the Earth's mantle

Sep 3, 2014 Publication in Acta Materialia Results

Atomic core structure and mobility of [100](010) and [010](100) dislocations in MgSiO3 perovskite.

 co-authored by P. Hirel, A. Kraych, P. Carrez & P. Cordier has just been published in Acta Materialia, 79, 117-125, doi: 10.1016/j.actamat.2014.07.001

We have modeled the atomic configuration and the movement of [100](010) and [010](100) dislocations in MgSiO3 perovskite (bridgmanite)

 

Mg-Pv_screw

Atomic configuration of the [100] screw dislocation viewed in the (010) plane.

 

Computer models allow to predict the planes in which the dislocations glide, and the stress required to make them move. The higher the pressure, the more difficult it becomes for dislocations to move. One type of dislocations, the [010] edge, is even found to become completely immobile above a certain pressure due to climb dissociation (see below) :

 Mg-Pv_edge

 

We have also shown that dislocations in MgSiO3 have little to do with those encountered in other materials with the perovskite structure, meaning that it is difficult to establish general rules and each of these materials has to be studied thoroughly.