A two-dimensional model describing the oxygen ordering in the CuO1-del
ta basal plane of Y Ba2Cu3O7-delta is studied using the molecular-dyna
mics technique. We report the evolution of the system with delta = 0.5
and delta = 0.3 quenched from OI to OII phase and from tetragonal to
OII phase. Depending on the oxygen concentration, annealing of quenche
d OI phase leads either to the formation of OII precipitates within OI
phase or antiphase domains of OII phase.