Effect of SiC Content on Structural, Optical, and Dielectric Characteristics of PVA-Based Nanocomposites: A Comprehensive Study

Abstract In this study, SiC nanostructures in the form of nanowires have been synthesized by carbothermal reduction method at 1800°C, and SiC/Polyvinyl alcohol (PVA) nanocomposites with various filler contents (1‒10 wt %) have been obtained. X-ray diffraction (XRD) analysis confirmed the presence of the cubic β‑SiC (3C-SiC) phase together with the semi-crystalline structure of the PVA matrix. Using the Williamson–Hall method, the crystallite size for pure SiC was 13.84 nm and the microdeformation was −3.25 × 10–3; the crystallite size for pure SiC was 39.23 nm using the Debye–Scherrer formula. In the compositions, at an increase in the fraction of SiC (1 → 7 wt %), the crystallite sizes decreased from 28.7 to 12.53 nm, and at 10 wt %, they increased to 13.94 nm. Optical analysis (Tauc plots) has revealed a narrowing of the band gap from 5.74 eV (PVA) to 4.99 eV (5 wt % SiC). The optical band gap (Eg) was not determined for the 7 and 10 wt % samples due to complete light absorption, which obscured the absorption edge. An inverse correlation between the crystallite size and Eg that is caused by interphase interactions of SiC nanowires with PVA hydroxyl groups and an increase in defect density has been established. The optimal concentration from the point of view of dispersion and structural stability was determined to be 7 wt % SiC/PVA.