Influence of graphene oxide on crystallite size, lattice strain, and porosity in FeGaInS₄/PVA composites

Polyvinyl alcohol (PVA) nanocomposites reinforced with FeGaInS 4 and graphene oxide (GO) were investigated to enhance their structural and morphological properties for advanced functional applications. This work aims to understand how two different two-dimensional layered fillers influence the polymer composite’s structure, morphology, and potential application in optoelectronics and energy storage devices. The nanocomposites were synthesized using a solution-casting method and characterized by x-ray diffraction, Fourier-transform infrared spectroscopy, Raman spectroscopy, and field-emission scanning electron microscopy. The incorporation of FeGaInS 4 reduced the crystallite size from ∼30 nm to ∼8 nm and shifted the microstrain from tensile (0.34 × 10 −6 ) to compressive (−17 × 10 −6 ), indicating enhanced structural compaction due to polymer–filler interactions. Subsequent addition of GO at 1 wt.% and 3 wt.% further modified the strain to −10.28 × 10 −6 and −6.47 × 10 −6 , respectively, attributed to improved interfacial bonding and stress relaxation. GO also decreased defect density and increased porosity by disrupting the PVA network. These synergistic effects between FeGaInS 4 and GO demonstrate the tunability of the nanocomposite structure, offering a pathway for tailored materials in optoelectronic and energy storage applications.