The effects of ion bombardment on multicomponent oxides, such as PbTiO3, and multilayer systems have been extensively studied by an in situ stress measurement technique. Energetic ion bombardment was found to accelerate PbTiO3 formation. Both the annealing temperature and the time needed for completion of the reaction were reduced. The apparent activation energy responsible for stress relaxation was found to be 310 kJ/mole for ion-assisted deposition (IAD) films, which is 120 kJ/mole higher than that for non-IAD films. This was attributed to stress reduction in PbTiO3 thin films resulting from ion bombardment. In addition, effects of ion bombardment on the stress of as-deposited multilayers, on the stress development in multilayers during annealing, and on the structure-property-processing interrelationships were also investigated.