Pathway for a martensitic quartz-coesite transition.

An atomistic pathway for a strain-induced subsolidus martensitic transition between quartz and coesite was found by computing the set of the smallest atomic displacements required to transform a quartz structure into a coesite structure. A minimal transformation cell with 24 [Formula: see text] formula units is sufficient to describe the diffusionless martensitic transition from quartz to coesite. We identified two families of invariant shear planes during the martensitic transition, near the {10[Formula: see text]1} and {12[Formula: see text]2} set of planes, in agreement with the orientation of planar defect structures observed in quartz samples which experienced hypervelocity impacts.