Physical study on nife2o4/α- Fe2O3 composite-thin films for potential applications

This work highlights some physical investigations on NiFe2O4/ alpha- Fe2O3 composite deposited on glass substrates as thin films at T = 460 degrees C by the spray pyrolysis technique. First, X-ray diffraction analysis approved the polycrystalline nature of such films with a mixture of NiFe2O4 and alpha- Fe2O3 materials. The majority phase based on NiFe2O4 compound indicated the achievement of a cubic structure and the preferred orientation of the crystallites are along (311) direction while alpha- Fe2O3 is a minority phase crystallizing in rhombohedra structure. Raman spectroscopy measurement depicts the presence of cubic structure of NiFe2O4. Moreover, the reflectance and the transmittance optical coefficients increase with wavelength and do not exceed 45% which reveals an absorbent character of these films. Second, we evaluated the electrical properties of such films at various temperatures (430-490 degrees C) by using the impedance spectroscopy technique in frequency range of 5 Hz-13 MHz. Both the DC conductivity and relaxation frequency were thermally activated with an activation energy around 0.67 eV. Also, AC conductivity was estimated and deeply discussed through Jonscher law. Nonetheless, the electropyroelectric study of these films has been made and discussed. Also, the wettability experiments have been carried out regarding the contact angle CA which reveals a hydrophilic nature of NiFe2O4 / alpha- Fe2O3 sprayed thin films. Finally, the photocatalytic activity of these films were carried out regarding the photodegradation of methylene bleu (MB) under sunlight during 120 min.