diffusional transition

A transition that requires the @R05194@ of atoms, ions or molecules in a manner that cannot be accomplished by a cooperative atomic displacement; it may require the movement of atoms, ions or molecules over distances significantly larger than a @U06562@. Example: The transition of @G02684@ (hexagonal sheets of three-coordinated carbon atoms) to @D01671@ (infinite three-dimensional framework of four-coordinated carbon atoms) at high temperature and pressure.
PAC, 1994, 66, 577. (Definitions of terms relating to phase transitions of the solid state (IUPAC Recommendations 1994)) on page 581 [Terms] [Paper]