Synthesis of nanocomposite metallic oxides in a doped low- pressure flame reactor

The importance of nanosized material in many contemporary applications is already known. However special properties such as superparamagnetism, semi-conducting and photocatalysis are unique to single metallic oxide. Recent advances in information technology, catalysis, and medicine often require materials that posses a combination of two or more of these properties. Nanocomposite materials present a possibility of having several unique properties within a compact material system. Modern synthesis techniques such as chemical vapour deposition and sol-gel process, becomes seemingly complicated when more than one component is involved. This has necessitated the need to have a synthesis process that is reliable and uncomplicated. In this study, a H2/O2/Ar flame is presented as a possibility for synthesis of TiO2 and Fe2O3 based nanocomposites. The kinetics of nanocomposite flame synthesis begins with thermal dissociation of the metalorganic precursors due to the high flame temperature. Free radicals resulting from the H2 oxidation eventually react with precursor material to form primary particles. Growth occurs by collision between primary particles followed by coalescence by either viscous flow mechanism for liquid particles, or by solid state diffusion if the particles are in the solid phase [1]. The final primary particle size depends on the temperature-time history as functions of the surface growth rate and residence time. TiO2-SnO2 mixed oxide nanoparticles 5 nm ≤ dp ≥ 12 nm were synthesized in a low pressure premixed flame with Titanium tetra iso-propoxide (TTIP) and Tetramethyltin (TMT) as precursors [2]. The effect of varying TTIP and TMT concentrations on the energy band gap of the mixed oxide was investigated. BET, XRD, TEM and UV-VIS were employed to effectively characterize this composite system. It was observed that the particles have a spherical morphology but show strong agglomeration. XRD did not indicate separate peaks of TiO2 and SnO2, hence indicating the absence of a segregated system. New lattice parameters calculated from the XRD indicates varying composition of Ti and Sn within the mixed oxide. It was further deduced that TNT2004 September 13-17, 2004 Segovia-Spain