Influence of gadolinium doping on structural, optical, and magnetic properties of CuS nanostructures

To examine the effect of rare earth ions on CuS nanostructures, a series of Gadolinium-doped copper sulphide (Cu1-xGdxS) nanostructures were synthesized through the hydrothermal method. These nanostructures were prepared at x = 0, 1, 3, 5, and 7 at. % concentrations. The prepared samples' structural, optical, and magnetic characteristics were investigated. Powder X-ray diffraction and Raman analysis were performed to examine the structural analysis of the samples and confirm the existence of a covellite phase hexagonal structure. XPS analysis was conducted to study the valence states. Observations of the surface morphology study from FESEM reveal the formation of flower-shaped structures resembling nanospheres, while at lower magnification nanoflakes were observed. Optical reflectance spectra were recorded using UV-Vis spectroscopy, which showed the increase in bandgap as the concentration of Gd rises. The fluorescence spectrophotometer was utilized for the analysis of room-temperature photoluminescence. The prepared samples showed significant emission peaks at 435 nm. Fluorescence lifetime studies were carried out to confirm the fluorescence decay of CuS nanostructures doped with Gd. Magnetic measurements revealed that prepared samples exhibit an unexpected superparamagnetic nature at room temperature.