Study On The Preparation, Characterization And Properties Of Co And Ni Doped ZnO Nanostructures

Zinc oxide nanostructures is of great potential in various practical applications, such asspin functional devices, UV-light emitters, sensors, and piezoelectric transducers etc. In lastdecade, metal ions-doped ZnO nanostructures are attracting much attention for theirimproved properties. The objective of this thesis is to prepare Co and Ni doped ZnOnanostructures by electrodeposition and sol-gel methods. The dependence of theirproperties and the microstructure on preparation condition is studied via thecharacterization of microstructure, optical and magnetic properties. Further discussionrevealed the photoluminescence and the origins of room ferromagnetism. The maincontents of the research are summarized as follows:1. Highly uniform porous AAO membranes with different pore diameters were fabricatedin0.3M H2C2O4electrolyte and1M H2SO4electrolyte using two-step anodic oxidation.The morphologies of AAO membranes were characterized by the field emission scanningelectron microscope （FE-SEM, JSM-6700F）. The techniques, mechanics and influencingfactors of AAO membranes were also analysed in detail. We invented a method that cansimply and fast remove the Au film sputtered on AAO membranes. Co-ZnO Nanorods wereobtained by electrochemical depositing Co-ZnO into the AAO membranes. The FE-SEMimages and EDS are used to analyze the morphology and components, respectively.UV-vis-NIR spectroscopy was also used to measure the light absorption of Co-ZnONanorods. It was found that Co doping helped to broaden the ZnO band gap.2. Co-ZnO thin films with highly c-axis orientation have been fabricated byelectrochemical deposition and sol-gel methods. The morphologies and elementalcomponents of samples synthesized in different temperature and PH values of solution, andelectric plating current values in solution were compared to make up a optimizedprescription. The x-ray diffraction （XRD） results of sample A show that all films are ZnOwurtzite without impurity phases. It has been characterized by SEM, PL, XPS, andvibrating sample magnetometer（VSM） measurement, which indicates that Co²⁺interstitialswere doped into ZnO crystal lattice. Co-ZnO films present room temperatureferromagnetism, which resulted from the coupling effect Co²⁺and carriers.3. One-step electrodeposition of Ni-ZnO thin films on polycrystalline Zn foils at70℃.the mechanics of the Ni-ZnO films were studied. Their photoluminescence at room temperature showed redshirts and weak peaks emission peaks, which was attributed to theresult of Zn defects and oxygen vacancy defects with Ni doping.