Composition Influence on the Properties of Titanium-Doped Gamma Iron Oxide Nanoparticles Prepared by Laser Pyrolysis Met
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J13.5.1
Composition Influence on the Properties of Titanium-Doped Gamma Iron Oxide Nanoparticles Prepared by Laser Pyrolysis Method Ion Morjan1, Rodica Alexandrescu1, Florian Dumitrache1, Ion Sandu1, Monica Scarisoreanu1, Lavinia Albu1, Iuliana Soare1, Ion Voicu1, Bohumil David2, Oldrich Schneeweiss2, Claudiu Fleaca1, Ernest Popovici1 and Victor Ciupina3 1
Laboratory of Laser Photochemistry, National Institute for Lasers, Plasma and Radiation Physics, P.O.B MG-36, 077125 Bucharest, Romania 2 Institute of Physics of Materials, AS CR, Brno, Czech Republic 3 Ovidius University, Constanta, Romania ABSTRACT The aim of this work is the structural and sensing characterization of titanium-doped gamma iron oxide nanocomposites. These nanopowder materials were synthesized by the laser pyrolysis technique. It is based on the resonance between the emission of a CW CO2 laser line and the infrared absorption band of a gas (vapour) precursor. Basically, sensitised iron pentacarbonyl and titanium tetrachloride-based mixtures were used as gas-phase reactants. The compositional characterization of the synthesized nanostructures was performed by means of different analytical techniques. Introducing Ti in the Fe2O3 network in small quantities (< 1 %) seems to have little influence on titanium doped powder morphology (mean grain size ~ 5nm) but increases the sensitivity of titanium doped iron oxide nanopowders with more then 20 % relatively to pure maghemite. INTRODUCTION Complex metal oxides have applications in high-technology areas such as batteries, superconductors, vehicle emission control, solid oxide fuel cells, sensors and catalysts. As gas sensing devices, they can operate at elevated temperatures and are relatively inexpensive. The sensing capabilities are dependent upon their nanoscale morphology [1, 2]. There is a current industrial interest in nanophase iron and iron-based compound materials. Particularly maghemite is a very important magnetic material that is isostructural with magnetite but with cationdeficient site [3]. The doping of γ-Fe2O3 (maghemite) has attracted attention because of its applications in magnetic and sensing materials and in biotechnology. Data concerning the doping with tetravalent metals such as titanium [4, 5] are of great interest also because of the occurrence of titano-maghemite in nature and because substitution with tetravalent ions can be used to stabilize γ-Fe2O3 (maghemite) against transformation to α-Fe2O3 (hematite) at elevated temperatures. Laser pyrolysis from the gas phase is a vapour phase method of synthesis where the reactants are dilute and therefore yield a fine, loosely agglomerated powder, narrow particle size distributions, and controlled purity [6]. We have previously reported on the preparation of single maghemite [7, 8] and titania nanoparticles [9] by the use of the laser pyrolysis method. Employing the same laser technique, we present now comprehensive investigations of titaniumdoped iron oxide nanostructures. Sensitized iron pentacarbonyl and titanium chloride-based mix
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