Correlation of synthesis parameters to the phase segregation and lattice strain in tungsten oxide nanoparticles

Crystalline phase, crystallite size, and lattice strain have an important role in designing the state of art technology using different metal oxide nanostructures. Herein WO 3 nanopowder was synthesized by facile precipitation method using WCl 6 as precursor and water as a solvent. The effect of various parameters like urea (used as a capping agent), pH, temperature and different surfactants (CTAB (Hexadecyltrimethylammonium bromide) as cationic, SDS (Sodium dodecyl sulfate) as anionic and Tween20 as non-ionic has been studied on crystalline phase, crystallite size and lattice strain of WO 3 nanopowder. The study of crystalline phase and crystallinity behavior was done by using x-ray diffraction spectroscopy. Crystallite size and lattice strain were calculated using two different ways i.e. by Debye Scherer's formula and Williamson-Hall method via three different models: uniform deformation model, uniform deformation stress model, and uniform deformation energy density model. Surfactant-assisted WO 3 nanostructure yield monoclinic phase at a higher temperature while urea capped samples give monoclinic phase at a lower temperature. Another phase orthorhombic tungstite (WO 3 .H 2 O) is observed to be at a lower urea concentration. Surfactant-assisted nanopowder has observed to show tungstite phase at a lower temperature. Besides this, an acidic environment is more suitable for the formation of orthorhombic tungstite nanopowder.