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Characterization of maghemite thin films prepared by sol-gel processing

Karakuşçu, Aylin
In this study, maghemite (γ-Fe2O3) thin films were prepared by chemical solution deposition on glass and quartz substrates. The solution was prepared by using 0.3 M iron (III) nitrate [Fe(NO3)3 - 9H2O] as precursor and dissolved in a mixture of 2-methoxyethanol and acetylacetone in a molar ratio of 20:2, by stirring the solution at RT for 2 hours. Substrates were prepared by either piranha etching method or ultrasonic cleaning method. The solution was spin coated on glass and quartz substrates at 1400 and 4000 rpm for 1 minute. The resultant film thickness was found as 65 and 80 nm by SEM. Viscosity of the main solution was found to be approximately as 0.0035 Pa.s by viscosity measurement. TGA/DTA analyses showed that, to produce maghemite thin film, heat treatment should be done between 330 °C and 440 °C. Homogeneous and crack free maghemite thin films were observed by Energy Dispersive Spectrometry (EDS) and Scanning Electron Microscope (SEM) methods. TEM studies verified maghemite thin film formation by using electron diffraction and SAED (selected area electron diffraction) method. Thin film characteristics were evaluated by changing the experimental parameters which are annealing temperature, annealing time and thickness of the films using XRD (x-ray diffraction) method. Optical band gap of maghemite thin films were found as approximately 2.64 eV by UV-VIS Spectrophotometer. Magnetic properties of maghemite thin films were also examined by VSM (vibrating sample magnetometer).