High neutron-flux and improved detectors allow faster data acquisition; if suffi­ciently fast compared to the reaction rate, in situ kinetic studies are possible. The sensitivity of neutron diffraction to the crystallographic phases and the rate of data acquisition can allow not only the equilibrium state, but any intermediate phases and reaction rates to be determined.

To study the kinetics of phase transformations, hyper-stoichiometric uranium oxide was cycled across a phase boundary [57]. Desgranges et al. [58] performed in situ studies on transitions between four different uranium-oxide phases which depended on both temperature and oxygen partial-pressure. Knowledge of inter­mediate phases led to a better understanding of the phase-transition process and growth kinetics.