Effects of Cr-doping on the optical and magnetic properties in ZnO nanoparticles prepared by sol-gel method

The undoped ZnO nanoparticles and the Cr-doped ZnO nanoparticles were successfully synthesized by the sol-gel method. The structure, the optical characteristics and the magnetic properties of the produced samples were studied. The results indicated that Cr ions substituted for Zn ions successfully and the Cr-doping restrained the growth of the crystal lattice. The Cr ions exhibited +3 valence state other than +2 valence state. The dopant concentration was about 3 atm% in the Cr-doped ZnO nanoparticles, which was consistent with the design of our experiment. Compared with the photoluminescence (PL) spectrum of the ZnO nanoparticles, the peak position of ultraviolet (UV) emission of the Cr-doped ZnO nanoparticles exhibited blue shift, and the deep level emission band was sharply suppressed. Moreover, the Cr-doped ZnO nanoparticles had good ferromagnetic property at room temperature. (C) 2009 Elsevier B.V. All rights reserved.