A domain structure based on the rutile lattice with a large density of 1/2 < 011 >{011}-type stacking faults is found in sputter deposited TiO2 films [J. Vac. Sci. Technol. A 24, 2054 (2006)]. The thermal stability of nanomosaic rutile at moderate temperature is reported here. Films are annealed at 973 K for 0.25-15 h, characterized by x-ray diffraction. A Johnson-Mehl-Avrami-Kolmogorov analysis indicates impeded crystallite growth. A dislocation-locking mechanism is proposed for this behavior. Partial dislocations with 1/2 < 011 > Burgers vectors that bound the stacking faults glide on intersecting {011} slip planes and react to produce sessile stair rod dislocations. Without the high temperature required for dislocation climb, 1/2 < 011 >{011}-type faults inherent to nanomosaic rutile provide thermal stability against massive crystallite growth. (C) 2009 American Vacuum Society. [DOI: 10.1116/1.3139900]