Self-assembling spherical colloidal SiO 2 nanoparticles using shear flow leads to the formation of the films, consisting of aligned one-layer microfibers. The termination of fabricated microfibers and films can be described in terms of crystallographic faces of corresponding close-packed structures, which in turn are preset by the kinetic conditions of crystallization. An in-situ X-ray study of the transformation of the nanocrystalline microfibers at high-temperature into a mixture of silica polymorphs with the high-temperature β-cristobalite and tridimite as major components is performed. Microfibers heated in the middle temperature zone exhibit graded morphology, with the degree of coalescence of amorphous nanoparticles changing along the microfiber length. The performed study can be considered as a part of the development of a strategy (which could require both self-assembly and template-assisted steps) toward a bottom-up approach to the design of nanostructure arrays for technological applications.