XPS studies and Kramers-Kronig analysis of the optical properties of ZnO/SnO2 nanocomposites synthesized by gelatin-based sol-gel method

Abstract

Gelation-based sol-gel method was used to synthesize (ZnO)1-x/(SnO2)x nanocomposites (x = 0.0, 0.02, 0.04, and 0.06 which are indexed as ZnO, ZS2, ZS4, and ZS6, respectively). X-ray diffraction analysis (XRD) were used for the investigation of the structural characteristic of the prepared nanocomposites. The crystallite sizes were calculated by using size strain plot method (SSP). Ultraviolet–Visible (UV–vis) and X-ray photoelectron spectroscopies (XPS) were carried out for the optical characterizations. The obtained reflectance data from the UV–vis spectroscopy were analyzed by using Kramers-Kronig mathematical method to study the behavior of the refractive index and permittivity of the samples. Transmission electron microscopy (TEM) observations were used to study the particles sizes and morphologies variations. According to the obtained results, Sn4+ ions could not diffuse into the ZnO lattice structure and therefore, SnO2 nanocrystals growth beside the ZnO nanocrystals resulted in (ZnO)1-x/(SnO2)x nanocomposites. Although Sn4+ ions had not incorporated into Zn2+ sites, the optical properties of the fabricated nanocomposites were significantly changed and the transparency of the samples increased.