Analysis of the morphology, structure and optical properties of 1D SiO2 nanostructures obtained with sol-gel and electrospinning methods

The aim of the study was the production of ceramic SiO2 nanowires using the sol-gel and electrospinning methods from a PVP/TEOS/AcOH/EtOH solution. The obtained fibrous mats underwent preliminary drying at room temperature. Then, they were subjected to the calcination process in air to obtain pure amorphous silicon dioxide nanowires. A scanning electron microscope (SEM) with an energy dispersive spectrometer (EDS) was used in order to carry out an analysis of the morphology and chemical composition of the resulting nanowires. A high-resolution transmission electron microscope (TEM) was used along with X-ray diffraction analysis (XRD) in order to analyse the structure of the obtained materials. Besides, thermogravimetric analysis (TGA) was performed to show polymer concentration loss in the function of temperature in the obtained two types of PVP/SiO2 nanofibers. The analysis of the optical properties and the energy band gap of the prepared nanowires was determined by spectral analysis using a UV-Vis spectrophotometer. Using the method proposed by the authors and the recorded absorbance spectra determined the banded refractive index n, real n' and imaginary k part of the refractive index as a function of the wavelength, complex dielectric constant epsilon, real and imaginary part er and epsilon(i) of the dielectric constant as a function of the wavelength of the SiO2 nanowires. The obtained results, which were as follows: energy band gap of 3.93-3.97 eV, complex refractive index coefficient values of 1.52-1.65 and dielectric constant in the range of 2.30-2.73, suggest the possibility to control the morphology and optical properties of the produced nanomaterial.