32 Proc. of the Sixth International Conference on Advances in Computing, Electronics and Communication - ACEC 2017. Copyright © Institute of Research Engineers and Doctors. All rights reserved. ISBN: 978-1-63248-138-2 doi: 10.15224/ 978-1-63248-138-2-07 Impact of Iron Doping on Structural and Optical Properties of Titanium dioxide Asfandyar Imtiaz 1 , Mashhood Ahmad 1 , Attaullah Shah 2 , Saifullah Awan 1 1 Department of Electrical Engineering, College of Electrical and Mechanical Engineering, National University of Sciences and Technology, Islamabad, Pakistan. 2 National Institute of Lasers and Optronics, Islamabad, Pakistan. Abstract— Pure and Fe +3 doped titanium dioxide thin films were prepared by sol-gel spin coating technique. Phase analysis, crystallite size, dislocation density and toughness of films were scrutinized by X-ray diffraction (XRD). The principal phase in the films was anatase. Crystallite size plummeted from 39.3 to 33.22nm whereas dislocation densities escalated from 6.47 x 10 -4 to 9.06 x 10 -4 (nm) -3 when Fe +3 content rose from 0 to 10%. These mushroomed dislocation densities imparted strength to the films on account of grain boundary strengthening phenomenon. Principal anatase phase of the films was validated by Raman spectroscopy. Minor peak broadening and peak shifting was observed for doped films, that were attributed to the dislocation induced stresses by the rising Fe +3 content. UV-Vis spectrophotometry was undertaken to ascertain the transmittance of films in ultraviolet and visible spectrums. The films exhibited substantial transmittance in the visible region but there was a vivid landslide from 78 to 37% with elevation of Fe +3 content. In order to establish the band gap reduction in doped films, Tauc plot was utilized. Band gap abated from 3.24 to 3.08eV with burgeoning Fe +3 content from 0 to 10% so that effective photocatalytic activity can occur in the visible spectrum as well. Keywords— Fe +3 doped, Anatase, Crystallite size, Dislocation density, Band gap, Tauc plot, Photocatalytic I. Introduction Titanium dioxide (TiO 2 ) is a distinguished n-type metal oxide semiconductor with loads of wide ranging beneficial properties that can be exploited to serve the various facets of human life. TiO 2 has received great attention since the last two decades owing to its high refractive index, large dielectric constant, immense physio-chemical stability, colossal inertness in austere ambiences, reduced toxicity, low cost and hassle free developmental methods. Presently, TiO 2 is actively employed in optoelectronic sensors [1], waveguides [2], photovoltaic cells [3], photo catalysts [4], as pigments in paints [5] and food (for colouring and additives), biomaterials (as bone substituents and cardiovascular implants) [6] and neutralizing agent against microbial organisms [7]. Authors Names & Affiliation Asfandyar Imtiaz National University of Sciences & Technology, Pakistan. Mashhood Ahmad National University of Sciences & Technology, Pakistan. Attaullah Shah National Institute of Lasers & Optronics, Pakistan. Saifullah Awan National University of Sciences & Technology, Pakistan. TiO 2 , being a remarkable photocatalyst in UV region, lacks photophysical properties in visible region due to its large bandgap (3.25 eV). UV constitutes round about 5% of the solar spectrum and this constraint curtails its effectiveness, thus rendering merely 1% solar energy conversion. Moreover, the photogenerated electron hole pairs exhibit tremendously high recombination time, consequently further marring its reliability as photocatalyst. Hence, much research has been directed to redress these problems. Researchers have endeavoured to reduce the band gap by doping and surface decoration. Others embarked on the mission to reduce the recombination time by altering the size and shape of crystallites and incorporating charge traps and forbidden energy levels in the band gap region. Variety of methods have been proposed and implemented to successfully incorporate dopants within TiO 2 like anodization, chemical vapor deposition, sputtering, and plasma spraying [8]. The downside of aforementioned techniques is that they are hugely expensive and require scrupulous care to acquire the targeted objectives. Therefore, sol-gel approach provides an easy way out as it’s straightforward and cost effective at the same time [9]. In this paper, structural and optical features of iron (Fe +3 ) doped TiO 2 thin films prepared by sol-gel method have been rigorously analyzed. The crystal structure and different phase presence were studied through X-ray diffraction (XRD). Vibration modes were probed through Raman spectroscopy to acquire the finger print of the thin films grown. Transmittance and band gap variations were investigated through spectrophotometry. II. Experimental work The sol gel technique entails hydrolysis of metal alkoxides in alcoholic medium in the presence of acid catalyst. The acid works as chelating agent at the same time thus ensuring stability of the structure. In this study, ethanol (C 2 H 5 OH) was utilized as alcoholic solvent. Acetic acid (CH 3 COOH) performed the role of chelating agent and the metal alkoxide employed was titanium isopropoxide (TIP) Ti{OCH(CH 3 ) 2 } 4 . 0.12 M solution of 11.40ml of Ti was made. The technique involves taking 10ml of ethanol and mixing it with 1ml of acetic acid and the mixture is stirred for 20 minutes on magnetic stirrer. Afterwards, 0.40ml of TIP in introduced drop wise slowly into the mixture while stirring. Now, stirring is carried out for an hour. That is the recipe for pure TiO 2 . For the case of Fe +3 doped TiO 2 , previous steps are implemented initially, followed by introduction of anhydrous iron nitrate (Fe(NO 3 ) 3 ) which serves as precursor of Fe +3 . This step requires massive stirring. Subsequently, the stirring is carried out for 24 hours to ensure thorough mixing. Eventually, we end up with neat transparent