Dislocation microstructures of polycrystalline MgSiO3 perovskite, synthesized in a

multi-anvil type high-pressure apparatus at 26GPa and 2023K for 600min, were

investigated using transmission electron microscopy. The recovered MgSiO3

perovskite displayed deformation lamellae under cross-polarized optical

microscopy, suggesting that the sample was deformed during the high-pressure

experiment. Transmission electron microscopic observations showed that curved

dislocations with Burgers vectors lying in the {110} plane, potentially b = <110>

and [00w] (orthorhombic symmetry) were nucleated. Low-angle tilt boundaries

controlled by <110> dislocation climb were also activated at high temperature and

pressure. The potential Burgers vector of b = <110> was consistent with previous

results of slip to <100>cubic, [100]pc and [010]pc (cubic symmetry and pseudo-cubic

symmetry) on non-silicate perovskite analogues deformed at high temperatures and

ambient pressure. The microstructures of climb-accommodated dislocation creep

controlled by diffusion in the MgSiO3 perovskite can provide useful information on

the rheology at high temperatures and slow strain rates corresponding to the Earth's

lower mantle.

Dislocation Microstructures of MgSiO3 Perovskite at a High Pressure and

Temperature Condition. N.Miyajima, T.Yagi, M.Ichihara: Physics of the Earth and

Planetary Interiors, 2009, 174[1-4], 153-8