DAV International Journal of Science Volume-3 Issue-1 2014 ISSN: 2277-5536 (Print); 2277-5641 (Online) 12 SYNTHESIS AND CHARACTERIZATION OF -Fe 2 O 3 NANOPARTICLES AND THIN FILMS Kore E K 1 , Dhumal J G 2 , Zipare K V 3 and Shahane G S 1* 1 D B F Dayanand College of Arts & Science, Solapur, MS, India 2 School of Physical Sciences, Solapur University, Solapur, MS, India 3 C B Khedagi’s Arts, Science & Commerce College, Akkalkot, MS, India *E-mail: shahanegs@yahoo.com ABSTRACT Nanoparticles of iron oxide (-Fe 2 O 3 ) were prepared by chemical co-precipitation method. X-ray diffraction data confirms the synthesis of single phase of iron oxide (-Fe 2 O 3 ) nanoparticles with hexagonal structure. The lattice parameters are a= 5.038 and c=13.754 Å. The average crystallite size is 29 nm. FTIR analysis show absorption peak at 473.62 cm -1 corresponding to Fe-O bond which also confirms the formation of iron oxide. Iron oxide thin films were then deposited by spin coating technique. Optical study of the film showed strong absorption below 500 nm wavelength and high transparency towards red color. The band gap of -Fe 2 O 3 is found to be 2.65 eV with direct band to band transitions. KEY WORDS: Co-precipitation, hematite, Iron oxide, Nanoparticles. INTRODUCTION It is well known that α-Fe 2 O 3 (hematite) nanoparticles are particularly appealing for experimental and theoretical investigations in view of their technological applications. They have been widely used as red pigments, catalysts in dehydrogenation reactions, anticorrosive agents, and starting material in the synthesis of magnetic ferrites. Their applications in nonlinear optics and gas sensors have also been investigated recently (Dong et al., 2000). As a key component in modern image devices such as LCD panels and digital cameras, color filters are used to convert white light into the three basic colors to provide colorful images in conjunction with other component units (Wang et al 2010). For this, considerable efforts have been made in the synthesis techniques of iron oxide nanoparticles. Various processing routes such as chemical vapor deposition, sol-gel process, spray pyrolysis, chemical co-precipitation method, hydrothermal technique, forced hydrolysis, micro-emulsion technique, etc. have been developed for synthesizing iron oxide nanoparticles (Nidhin et al., 2008; Drbohlavova et al., 2009; Basavaraja et al., 2010; Shahane et al., 2010; Roshan et al. 2011). Among the various methods chemical co-precipitation is most suitable method as it has a better control on the size and shape of the synthesized nanoparticles (Shahane et al., 2010). This paper describes the synthesis and characterization of iron oxide (α-Fe 2 O 3 ) nanoparticles and thin films. EXPERIMENTAL DETAILS The nanoparticles of hematite having chemical formula Fe 2 O 3 are prepared by co-precipitation method using ferric chloride (FeCl 3 ) and ammonia solution (NH 4 OH) as the starting materials. Ferric chloride was dissolved in distilled water to form a clear solution. To this ammonia solution was added slowly. The pH of solution was adjusted to 8.5. The solution mixture was heated at 60 o C and stirred vigorously with a magnetic stirrer for about one hour. Oleic acid was added to serve as surfactant. Oleic acid covers the NPs and prevents agglomeration. The precipitate was washed several times with distilled water to remove the salts. The precipitate was then dried by heating in air using hot plate kept at 80 (for 2 hours). The solid product was then grind in an agate mortar to make them powder. The powder was annealed at 500 for two hours to improve the crystalline properties of the material. The crystalline phase of the prepared sample was identified by X-ray diffraction technique using RIGAKU make MINI FLEX II powder X-ray diffractometer with Cu radiation operated at 30 kV and 15 mA. Scanning was performed from 20 to 80 at a step size of 5 . FTIR transmission spectrum was recorded on Perkin Elmer Spectrum 65 Spectrometer from 4000 to 400 cm -1 . Iron oxide thin film was deposited on glass substrates by using a spin coating technique. The synthesized powder was dissolved in m-cresol and films were deposited using spin coating unit (MILMAN). The substrates were rotated at 3000 rpm for 2 minutes and then heated at 400 o C for 1 minute. The UV-VIS spectrum of nanocrystalline iron oxide thin film was recorded using Shimadzu UV-VIS-NIR spectrophotometer (UV-3600) from 300 to 800 nm wavelength range.