  In situ studies under severe plastic deformation at high pressures, employing
rotational/shear diamond anvil cells (RDAC), have recently gained much interest
in the high-pressure community owing to their potential applications in
material processing methods, mechanochemistry, geophysics, etc. These studies,
combined with multi-scale computational simulations, provide important insights
into the transient hierarchical microstructural evolution, structural phase
transitions, and orientation relationship between parent and daughter phases
and help establish the kinetics of strain-induced phase transitions under
severe plastic deformation. Existing RDACs are mostly used in axial x-ray
diffraction geometry due to geometrical constraints providing less reliable
information about stress states and texture. Their asymmetric design also poses
serious limitations to high-pressure shear studies on single crystals. To
overcome these limitations, a new compact symmetric rotational diamond anvil
cell has been designed and developed for in situ high-pressure torsion studies
on materials. The symmetric angular opening and short working distance in this
new design help obtain a more reliable crystallographic orientation
distribution function and lattice strain states up to a large Q range. Here, we
present the advantages of the symmetric design with a few demonstrative
studies.
