Composition dependent room temperature ferromagnetism and PL intensity of cobalt doped ZnS nanoparticles

ZnS:Co (0, 1, 2, 3 and 5 at.%) nanoparticles were synthesized by refluxing technique at 80 °C, with PVP as stabilizer. The effect of cobalt doping on the structural, optical and magnetic properties is investigated. EDAX spectra confirmed the presence of Zn, Co and S in the samples. X-ray diffraction patterns showed a single phase that of zincblende and Transmission Electron Microscopy (TEM) indicated that the particles were a few nm (<10 nm) in size. Diffuse Reflectance Spectroscopy (DRS) showed a slight increase in the band gap on doping which further attested the incorporation of Co2+ into ZnS nanoparticles as a substituent. Photoluminescence (PL) spectra showed enhanced luminescence intensity with increasing Co concentration. Room temperature magnetization studies revealed that all the Co doped ZnS nanoparticles exhibited ferromagnetic signal which became stronger with increasing Co content. Thus the present studies show that Co doped ZnS nanoparticles may find applications in photoluminescent and spintronic devices.