The effect of solvent on the structural, morphological, optical and dielectric properties of SnO2 nanostructures

We investigate the effect of solvent, i.e., ethanol and deionized (DI) water, on the structural, optical, and dielectric characteristics of SnO₂ nanostructures, synthesized via the hydrothermal method. Utilizing X-ray diffraction (XRD), we find the rutile phase for both nanostructures with average crystallite sizes of 12.53 nm and 6.62 nm for the samples synthesized using ethanol and DI water as solvents, respectively. The energy-dispersive X-ray spectroscopy (EDX) confirms the presence of Sn and O elements in both samples. Scanning electron microscopy (SEM) reveals that the samples prepared using ethanol and DI water exhibit nanorods and nanoflowers structures, respectively. The calculated band gap for SnO₂ based on ethanol and DI water solvents is found to be 3.54 eV and 3.45 eV, respectively. The SnO₂ nanostructure prepared by ethanol solvent demonstrates a higher dielectric constant which is attributed to higher defect density and more grain boundaries in it than in the sample synthesized using DI water. At low frequencies, the high tanδ values in the case of both nanostructures are explained based on space-charge polarization (SPC). The SnO₂ prepared by DI water exhibits higher tangent loss than the one synthesized using ethanol because of its significant surface area. The significant amount of conducting grains in the SnO₂ nanostructure while using ethanol solvent makes it a better conductive. Furthermore, the dielectric constant increases with increasing temperature which suggests considerable changes in the polarization behavior, while the tangent loss and conductivity demonstrate dependency on the temperature, indicating the promise of the nanostructures for electrical applications.