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Characterization of magnetite thin films produced by sol-gel processing

Eken, Ali Erdem
Magnetite (Fe3O4) thin films were prepared by a sol-gel process in which, a solution of iron (III) nitrate dissolved in ethylene glycol was applied on glass substrates by spin coating. Xerogel films were obtained by drying the coated films at 110 °C. The films were sintered between 300 °C and 450 °C in order to observe the phases existing in the films at different temperatures. Coating solution showed Newtonian behaviour and viscosity was found as 0.0215 Pa.s. DTA analysis showed that, sintering temperature should be selected between 291 °C and 350 °C in order to produce magnetite thin films. Prepared magnetite thin films were characterized by XRD, SEM, AFM, TEM, VSM and UV-Vis spectrometer. In-plane grazing angle diffraction studies showed that magnetite phase was present upon sintering the films at 300 °C. From the SEM studies, it was shown that films with defect free surfaces were obtained and by cross section studies, thickness of the films was found as ~10-200 nm. AFM images showed that no cracks or any other defects on the film surface were present. TEM results proved the existence of single phase magnetite in the produced films. UV-Vis spectrum results showed that transmittance of the films increases with decreasing sintering temperature and increasing spinning rate. Up to 96% transmittance was observed between the wavelengths of 900-1100 nm. Magnetic properties of magnetite thin films were also examined by VSM (Vibrating Sample Magnetometer) and ferromagnetic behaviour was shown using VSM data.