Study the impact of terbium additions in the microstructure, optical and electrical properties of polyvinyl alcohol

Films of pure polyvinyl alcohol (PVA) and their mixture with variable weights of terbium salt were prepared by the traditional cast technique. The composite samples were structurally studied by x-ray diffraction. The semi-crystalline nature was confirmed in the blend compositions. Via the FT-IR spectrum, the complex formation inside the polymeric samples between Tb³⁺ and hydroxyl groups in the PVA matrix was noticed. The particle agglomeration with various shapes was observed on the surface of the samples with the increase in the weight of Tb³⁺-salt by the SEM. The optical transmission and absorption spectra in the UV-Visible region showed that the intensity of the shoulder at 280 nm decreases and increases, respectively, by the increment of Tb³⁺-salt. The optical energy gap gradually decreased from 4.957 eV for undoped PVA to 3.470 eV for PVA:0.1 g Tb³⁺. Besides, the refractive index and dielectric of PVA were impacted by doping with Tb³⁺ ions. The AC conductivity of the composite films tracks the Jonscher's power law. The results show the ability to use the samples in multiple applications such as optoelectronic devices.