Microstructure and optical properties of NaTaO3 and TiO2 nanocrystalline low symmetry materials.

In this work, in order to study the correlation between the microstructure and optical properties of the low symmetry materials, two different nanopowders i.e. TiO 2 (tetragonal) and NaTaO 3 (orthorhombic) are synthesized by the sol-gel and hydrothermal methods, respectively. Based on the active slip systems in rutile crystals, the contrast factors of dislocations are calculated numerically for TiO 2 and then the microstructure behavior is investigated in terms of annealing temperature using the whole powder pattern modeling method. The NaTaO 3 is crystallized in perovskite structure with unknown slip systems, therefore the behavior of its microstructure is investigated by the Rietveld method. Furthermore, UV–Vis and photoluminescence spectra were measured for two series samples to find the relation between the optical and microstructure peculiarities. [ABSTRACT FROM AUTHOR]