Synthesis and characterization of polyvinyl alcohol-based ZnGa2O4 nanocomposites: structural, optical, and dielectric properties

Abstract

Herein, we present the synthesis of Gallium zinc oxide (ZnGa2O4) nanoparticles and fabrication of the polyvinyl-alcohol (PVA)-based nanocomposites (NCs) with varying weight percentages (wt.%) of ZnGa2O4 nanoparticles (0.5, 1.0, 2.0, and 4.0 wt.%) by solution casting method. The morphological and topographical features of the ZnGa2O4 nanofillers and PVA/ZnGa2O4 nanocomposites were investigated using X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The obtained data confirm the crystallinity and uniform dispersion of ZnGa2O4 in PVA/ZnGa2O4 nanocomposites. The optical properties, including the absorption coefficient, optical bandgap, refractive index, extension coefficient, optical conductivity, and Urbach energy, were calculated using data obtained from the UV-visible spectrometer. The absorbance analysis showed a reduction in the indirect bandgap of PVA and its nanocomposites from 5.57 to 3.48 eV and the direct bandgap from 5.49 to 3.52 eV. The optical properties of ZnGa2O4 nanocomposites such as refractive index, electrical conductivity, and extinction coefficient increased significantly with higher concentration of the dopant (0.0-4.0 wt.%). The electrical characteristics of the PVA/ZnGa2O4 nanocomposites, dielectric constant (epsilon '), dielectric loss (epsilon ''), and electrical modulus (real and imaginary part), as well as AC conductivity (sigma) were measured in the frequency range of 20 Hz to 1 MHz. As the filler content increased, the dielectric permittivity, dielectric loss, and electrical conductivity reduced with increasing filler content.