(359d) New Precursors Leading to Single Crystalline WO3 Nanospheres

Widely applicable Flame Spray Pyrolysis (FSP) route has been employed for the syntheses of spherical, single crystalline WO3 nanoparticles using tungsten precursors with the metal in usual and unusual oxidation states. The tungsten oxides have been characterized by powder X-ray diffraction and the patterns have been refined using Rietveld method (space group P21/n, monoclinic system; a = 7.300, b = 7.530, c = 7.680, β = 90.90deg, Z = 8, unit cell volume 422.1 A^3). The size of the particles obtained from different precursor solutions were in the range of 8-10 nm reasonably agreeing with the particle sizes determined from BET and microscopic analysis. The spherical morphology of the particles and well-developed lattice fringes with spacing of ~ 3.94 Å was determined by low and high resolution transmission electron microscopy (HRTEM) respectively for WO3 (obtained from different precursors). Line indexing of SAED patterns of all WO3 nanomaterials was isostructural with identical monoclinic phases. The precursors used to synthesize these nanopowders are inexpensive and easily available. The synthesis of WO3 nanostrutures using different oxidation states of W in the precursors is unusual but fascinating because it allows an elegant combination of high combustible organic solvent inspired morphosynthesis with FSP thermochemistry.