Fabrication of Luminescent, Magnetic Hollow Core Nanospheres and Nanotubes of Cr-Doped ZnO by Inclusive Coprecipitation Method

Incorporation of Cr into ZnO lattice as a dopant in hollow core nanostructures has been achieved by coprecipitation in highly alkaline medium near room temperature. Energy dispersive spectroscopy and X-ray diffraction studies confirm the presence of Cr in the ZnO lattice and X-ray photoelectron spectroscopy (XPS)identified the dopant state to be Cr3+. Room temperature ferromagnetism in ZnO:Cr3+ along with structural investigations suggest an intrinsic nature of ferromagnetism in hollow core nanospheres. Unpaired spin in Cr3+ in zinc substitutional sites could create spin ordering and long-range ferromagnetic coupling. Higher Cr3+ concentration leads to the formation of hollow parallelepipeds and superparamagnetism. Photoluminescence studies reveal a sharp blue emission explicitly arising due to Cr doping. Such blue emitting magnetic nanocapsules can have immense potential as biocarriers and also in spintronics