Study of the properties of zirconia nanoparticles/zinc oxide films composites: Comparation to thermally treated samples

Abstract

The aim of this study was to evaluate the effect the thermal treatment on the structural and optical properties of zinc oxide (ZnO) films and zirconia nanoparticles/zinc oxide film composites (ZrO2-nps/ZnO-films: Comp). X-ray diffraction (XRD) measurements indicated that structural properties of the ZnO and the ZrO2-nps/ZnO-films: Comp were improved after the thermal treatment at 500 °C for 24 h in air atmosphere. Field emission scanning electron microscopy images showed that the thermal treatment promoted a smoother surface in the ZnO films, and in the ZrO2-nps/ZnO-films: Comp it induced partial agglomeration of the ZrO2-nps. High resolution transmission electron microscopy confirmed the presence and the crystalline nature of the ZrO2-nps. The band gap calculated by UV–Vis measurements exhibited an opposite trend. In ZnO films the band gap was reduced after thermal treatment whereas in ZrO2-nps/ZnO-films: Comp the band gap increased after this posttreatment. PL measurements supported the XRD results due to the wide PL emission band in the visible region, which was partially splitted after the thermal treatment. In fact, the PL visible band corresponding to the ZrO2-nps/ZnO-films: Comp was weakened after the thermal treatment. Fourier transformed infrared spectra of ZnO films without and with thermal treatment were very similar, exhibiting the characteristic Zn-O vibration and a carboxylate band. However, for ZrO2-nps/ZnO-films: Comp the carboxylate band was almost imperceptible.

Keywords

• Zirconia nanoparticles
• Zinc oxide films
• Thermal evaporation
• Sputtering
• Thermal treatment