Structural, optical and magnetic properties of Gd/TiO2-reduced graphene oxide nanocomposites

The focus of the present work is to study the effect of reduced graphene oxide (rGO) on morphology, crystal structure and magnetic properties of Gadolinium (Gd)-doped TiO2 nanoparticles. Gd/TiO2-rGO nanocomposites are synthesised in two steps: sol–gel and hydrothermal method. The prepared composites are studied with XRD, Raman, HRTEM, PL, EPR and VSM for further analysis. XRD and HRTEM studies elucidate the crystallinity of the nanocomposite decreases with increase in Gd concentration. Electron micrographs of the samples reveal that both pure TiO2 and Gd/TiO2 nanoparticles are evenly decorated on the graphene sheets. Raman and PL spectroscopic techniques confirm the presence of oxygen vacancies (Vo) and surface defects. Enhanced optical absorption shows the interaction between Ti–Gd with rGO composites. Decrease in bandgap values may be understood by quantum confinement effect. The presence of singly ionised Vo is confirmed from EPR spectra which is responsible for weak ferromagnetic behaviour at room temperature. Moreover, magnetic studies show the concurrency of ferromagnetic and antiferromagnetic interaction that originates from different defects present in the Gd/TiO2-rGO nanocomposites.