Structure and properties variations in Zn1-xCoxO nanorods prepared by microwave-assisted hydrothermal method

ZnO and Co-doped ZnO nanopowders were synthesized by microwave-assisted hydrothermal method. The composition dependent morphology, structure, optical, and magnetic properties were systematically investigated. Self-assembly of nanoflower structure was obtained for ZnO nanorods without doping, but Co doping led to the disappearance of nanoflower feature. Structural and properties characterizations indicated that Co was incorporated into the Zn-site of ZnO lattice without formation of second phase. The intensity of photoluminescence spectrum decreased with Co doping although all samples showed blue emission. Co doping also led to a red shift in band gap due to sp-d exchange interaction between the band electrons and the localized electrons of Co2+ cations. In addition, the room-temperature ferromagnetism could be modified by the doping amount of Co.