Room Temperature Magnetism in Cobalt-Doped ZnS Nanoparticles

Cobalt (0, 1, 5, and 10 %)-doped ZnS nanoparticles have been synthesized via low-temperature solvothermal technique. The resultant nanoparticles have been analyzed using transmission electron microscope (TEM), electron dispersive spectroscope (EDS), X-ray diffraction (XRD), and UV-visible (UV-Vis.) and photoluminescence (PL) spectrophotometer. Magnetic studies have been carried out using a vibrating sample magnetometer (VSM). The average size of nanoparticles has been found to be ∼9 nm. The XRD spectra indicated cubic phase of the undoped and Co-doped ZnS nanoparticles. The band gap of doped nanoparticles, 4.80 eV, has been found to be blueshifted as compared to its undoped counterpart, 4.59 eV. Room-temperature emission spectra exhibited blue and green lines. Magnetic studies indicated diamagnetic and ferromagnetic character at lower Co concentrations, 0 and 1 %, and ferromagnetic and paramagnetic character at higher Co concentrations, 5 and 10 %.