Optical and magnetic properties of Co and Ni co-doped ZnS nanorods prepared by hydrothermal method

Undoped ZnS and doped Zn0.95-xCo0.05NixS nanorods with different concentration ratio (x = 0.01, 0.03 and 0.05) were successfully synthesized by hydrothermal method. The crystal microstructure, morphology, constituent elements, optical and magnetic properties of the samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), X-ray energy dispersive spectrometry (XEDS), Ultraviolet-visible spectroscopy (UV-vis), photoluminescence spectra (PL) and the vibrating sample magnetometer (VSM). All the samples synthesized by this method exhibit single phase wurtzite structure with good crystallization as demonstrated by XRD studies, which indicates that all Co2+ and Ni2+ successfully substituted for the lattice site of Zn2+ and generate single-phase Zn0.95-xCo0.05NixS. FESEM and HRTEM demonstrate that the morphology are one-dimensional rod-like shape with good dispersion. EDAX spectra confirmed the presence of Zinc, sulfur, Cobalt and Nickel elements with near stoichiometry. UV-vis spectra reveals the blue shift in the direct band gap of the co-doped ZnS nanorods. PL spectra shows obvious ultraviolet emission peak about 375 nm, and the blue emissions appear significant quenching phenomenon with the increasing of Ni2+ doping concentration. Magnetic measurements indicate that the undoped ZnS and co-doped samples are ferromagnetic behavior at room temperature.