This article deals with the synthesis, structural and optical characterizations of vanadium ion-doped ZnO nanoparticles. Four nanosized samples with a generic composition Zn$_{1–x}$V$_x$O (x = 0.00, 0.02, 0.04 and 0.06) were prepared using standard co-precipitation method. X-ray diffraction studies confirmed the existence of hexagonal wurtzite crystal structure and phase purity of prepared samples. Mean crystallites size within the range of 25 ± 3 nm was obtained from Scherrer’s formula. The compressive microstrain in the pure ZnO sample as obtained from Williamson–Hall plot ensured the presence of vacancies inside the nanocrystals. The surface morphology of doped ZnO nanocrystals was studied using field-emission scanning electron microscope image. Undoped ZnO nanoparticles showed a strong optical absorption near 390 nm. A redshift in direct bandgaps with increasing vanadium ions in ZnO matrix was noticed. Vanadium ions were present in three different oxidation states (+2, +3 and +4) within the host ZnO structure as obtained from X-ray photoelectron spectra. Photoluminescence studies also detected the existence of both zinc and oxygen vacancies in the synthesized nanoparticles.

This article reports the structural, magnetic and optical responses of Gd ion-substituted ZnO nanoparticles prepared via soft chemical co-precipitation technique. Both the hexagonal wurtzite crystal structure and crystallographic phase purity of all the samples were observed by using X-ray diffraction (XRD) technique. Three widely accepted methods, i.e., Scherrer’s approach, Williamson–Hall plot and Halder–Wagner method, have been used to determine the average crystallite size and microstrain within the nanosized ZnO crystals. Average crystallite size was obtained within the range of 23 ± 3 nm. Mean particle size obtained from HRTEM image was also found in good harmony with the XRD results. UV–visible spectra signified that all the nanosized ZnO samples manifested strong absorption in between 410 and 455 nm. The presence of both Zn and O vacancies in the samples was verified by the photoluminescence studies.Paramagnetic response of Gd ions in ZnO nanoparticles weakened the defect-driven magnetic behaviour at room temperature.