فهرست نشریات علمی دسترسی آزاد ایران

The ZnO, NiO and Fe2O3 oxides were deposited as thin films by pulsed laser deposition (PLD) at two energy densities (500 and 700 mJ). Therefore, the purpose of the work was to investigate the effects of processing energy on the structural, morphological, electrical and biological properties of the obtained films. X-ray diffraction (XRD) measurements confirmed that pure crystalline phases were obtained in all the samples (i.e. a wurtzite phase for ZnO, a rock-salt phase for NiO, and a hematite phase for Fe2O3). Crystallinity and grain size developed with increasing energy except NiO which showed abnormal behavior due to internal stresses. Field-Emission scanning electron microscopy (FE-SEM) demonstrated that the particles were mostly spherical and the size was controlled by the processing energy. Particle size was found to increase for ZnO and NiO while it was decreased for Fe2O3 when 700-mJ energy density was used, which can be attributed to an increased nucleation rate. Electrical measurements showed the films to be semiconducting in nature, and the conductivity was increased by post-deposition heating. The maximum conductivity was obtained for the samples which were prepared at 700 mJ, which was associated with higher crystallinity and lower structural defects. The conductivity was found to be in the following order: NiO, Fe2O3, ZnO. Metabolite bioactivities revealed obvious inhibition against Escherichia coli and Staphylococcus aureus, in which the inhibition strength increased with increasing energy density and concentration. ZnO showed the highest antibacterial activity with an inhibition zone of 32 mm against S. aureus followed by Fe2O3 and then NiO. These results highlight the important role that the surface structure plays in improving the biological performance of the thin films.