Synthesis And Characterization Of (Zno)–(Co3o4) Nanocomposite Via Spray Pyrolysis Process: The Use Of The Bruggeman Model On Optical Properties Prevision

In the present paper, (ZnO)–(Co3O4) nanocomposite thin films have been prepared by using spray pyrolysis deposition on a glass substrate at 350∘C. After that, the as-obtained films have been characterized and analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and the double beam UV-visible (UV-vis) spectrophotometer. Furthermore, the Bruggeman model is used to predict the evolution of the optical dielectric constant (real and imaginary parts: εr and εi) to compare them with those obtained from the experimental results. The XRD pattern reveals that the nanocomposite film has diffraction peaks 2θ=31.33∘, 36.95∘ corresponding respectively to the (220), (311) planes of cubic Co3O4 and another about of 2θ=36.26∘ corresponding to the (101) plane of Wurtzite ZnO. Using the Debye Scherrer formula, the crystallite size of (ZnO)0.5–(Co3O4)0.5 nanocomposite is found about 32nm, while the obtained thickness of this nanocomposite is about 780nm using the DekTak Stylus profilometer. Besides, the morphology analysis shows that the nanocomposite sample is well covered without holes and/or cracks and it has uniform dense grains. The evaluation of the transmittance, reflectance, refraction index, extinction coefficient, real and imaginary parts of dielectric constant as function of wavelength illustrates that the optical response of nanocomposite thin film (ZnO)0.5–(Co3O4)0.5 depends on the influence of two mediums of pure materials ZnO and Co3O4 and their interaction. In addition, the direct band gap vs incident photon energy obtained from the Tauc plot equation shows that this nanocomposite has three values of band gap energy which are Eg1=1.54eV, Eg2=2.2eV (correspond to pure Co3O4 film) and Eg3=3.47eV (correspond to pure ZnO film). Besides, the application of the Bruggeman equation indicates that the influence of the values of volume concentration and optical dielectric constant of the ingredient nanomaterials (ZnO and Co3O4) is significant on the value of the effective dielectric constant of nanocomposite thin film. The specific result of this study is the similarity between the spectra obtained from the Bruggeman model and the measured one, which proves that the application of this model is useful for the prediction of the optical properties of the composite.