Chromium doped ZnS nanoparticles: chemical, structural, luminescence and magnetic studies

Cr (0, 3 and 5 at.%) doped ZnS nanoparticles were successfully synthesized by hydrothermal method using PVP as capping agent. The influence of Chromium doping on the structural, luminescence and magnetic properties of ZnS nanoparticles is investigated. EDS spectra confirmed the presence of zinc, chromium and sulfur in the doped samples in near stoichiometric ratio. XRD and Raman analysis demonstrated successful incorporation of Cr³⁺ ions into ZnS lattice with the absence of metallic clusters or precipitates. TEM micrograph indicated that the particles were a few nm (<10 nm) in size. XPS results revealed that the Cr was incorporated into ZnS host lattice as Cr³⁺. Blue emission of ZnS was totally diminished by Cr doping. Magnetic studies revealed that the undoped ZnS display only diamagnetism whereas the Cr doped samples exhibited dopant induced room temperature ferromagnetism. EPR spectra of Cr doped ZnS nanoparticles reveal resonance signals near g = 2 corresponding to interacting Cr³⁺ ions. Hence, the present studies show that ZnS:Cr nanoparticles are promising materials for spintronic device applications.